ISO 28961, which describes the statistical distribution of hearing thresholds of otologically normal young persons, was established in 2012. The thresholds are those for pure tones of frontal incidence under binaural listening conditions in a free field. Percentiles of the threshold distribution are calculable as a function of frequency from 20 Hz to 16,000 Hz. This international standard is based on the study results of the present authors, who estimated the form of individual distribution using threshold data in their experiments and those in literature adopted in ISO 226 and ISO 389-7. However, because the results were published separately in four journal papers, users of the standard may encounter difficulty in understanding the process of how the threshold data have been integrated and how the threshold distribution has been determined. Therefore, the authors summarize them in this review paper and present an outline of the threshold distribution estimation so that the standard will be understood correctly and used widely. © 2013 The Acoustical Society of Japan.

The sensory unpleasantness of high-frequency sounds of 1 kHz and higher was investigated in psychoacoustic experiments in which young listeners with normal hearing participated. Sensory unpleasantness was defined as a perceptual impression of sounds and was differentiated from annoyance, which implies a subjective relation to the sound source. Listeners evaluated the degree of unpleasantness of high-frequency pure tones and narrow-band noise (NBN) by the magnitude estimation method. Estimates were analyzed in terms of the relationship with sharpness and loudness. Results of analyses revealed that the sensory unpleasantness of pure tones was a different auditory impression from sharpness
the unpleasantness was more level dependent but less frequency dependent than sharpness. Furthermore, the unpleasantness increased at a higher rate than loudness did as the sound pressure level (SPL) became higher. Equal-unpleasantness-level contours, which define the combinations of SPL and frequency of tone having the same degree of unpleasantness, were drawn to display the frequency dependence of unpleasantness more clearly. Unpleasantness of NBN was weaker than that of pure tones, although those sounds were expected to have the same loudness as pure tones. These findings can serve as a basis for evaluating the sound quality of machinery noise that includes strong discrete components at high frequencies. © 2013 The Acoustical Society of Japan.

2004年，耳覆い形イヤホンの基準等価閾値音圧レベルを規定したISO規格が発行された。それに伴い，従来から使用されてきた耳載せ形イヤホンに加えて，耳覆い形イヤホンが純音聴力検査に使用されることとなった。しかし，耳載せ形イヤホンと耳覆い形イヤホンでは，同じ条件で同じ者を測定しても，得られる聴覚閾値レベルは必ずしも一致しない。そのため，今後，両形のイヤホンが併用されるようになった場合，測定値の不一致による混乱が臨床現場で生じかねない。本研究では，同じ被験者を対象に，両形の複数のイヤホンを用いた聴覚閾値測定を行った。その結果に基づいて，異なる機種のイヤホン間で生じる聴覚閾値レベルの差を検討した。

Hearing thresholds for low-frequency complex tones were measured to investigate effects of intensity and frequency differences between components and effects of the number of components on the detection of complexes. Complex tones comprised two tones, geometrically centered at 60 Hz, with frequency differences of 30, 60, 90, or 120 Hz. Sound pressure levels of the two tones were set to equal intensity or to equal sensation level. Additional threshold measurements were conducted for complex tones comprising 2-6 components at 25-145 Hz. A complex signal with multiple tones was detectable even if the levels of individual components were below the threshold. The improvement of complex signal detection varied greatly with the level difference and number of tones. Threshold levels for complex tones (in terms of level per component) decreased as the number of tones increased. Complex tones whose components have mutually similar frequencies were more detectable than those with separated components.

This Technical Report presents air conduction hearing thresholds measured for pure tones at conventional audiometric frequencies (CAFs) from 125 Hz to 8 kHz and extended high frequencies (EHFs) from 8 kHz to 16 kHz, using apparatus and procedures in accordance with relevant ISO and IEC standards. The subjects were 490 otologically normal Japanese adults aged 18-83 years. Descriptive statistics of their threshold levels are presented in graphical and tabular forms to show the age-related decline of hearing sensitivity and its individual differences. The change in hearing sensitivity of older adults at CAFs was smaller, in general, than the standard values according to ISO 7029:2000, in which the amount of hearing sensitivity decline is estimated as a function of age. The threshold data presented in this report may serve as a basis for revising the international standard. In addition, measurement results at EHFs revealed that the responses of older subjects could be unreliable at the highest frequencies because of an unwanted sound in a lower frequency region generated with test tone presentation. Threshold values at extended high frequencies should be treated with caution. ©2011 The Acoustical Society of Japan.

Unwanted sounds from a commercially available audiometer were evaluated in terms of their effects on extended high-frequency (EHF) audiometry. Although the manufacturer reported that the audiometer conformed to relevant International Electrotechnical Commission (IEC) standards, the audiograms obtained using the audiometer were erroneous because the subjects had responded falsely to noise generated with the test tone presentation before detecting the test tone. Analyses of acoustic and electric output signals revealed that the audiometer generated most of the unwanted sounds, not the earphones that were used. Based on the measurement results, clinical implications of the measurement results are discussed for conducting more reliable EHF audiometry. (C) 2010 Acoustical Society of America

This Technical Report describes air conduction hearing thresholds measured for pure tones at conventional audiometric frequencies and extended high frequencies using apparatus and procedure in accordance with relevant ISO and IEC standards. The subjects were otologically normal Japanese high-school students aged 15-17 years. Descriptive statistics of their threshold levels are presented in graphical and tabular forms. Analyses of the measured data showed that the median threshold levels did not significantly deviate from the reference level of 0 dB and that they differed depending on the earphones used: supra-aural or circumaural earphones. These measurement results might be used effectively for revision of ISO 7029:2000, which describes the method for calculating the estimated hearing sensitivity decline as a function of age. © 2010 The Acoustical Society of Japan.

The audibility of pure tones presented against typical domestic sounds was investigated in a psychoacoustic experiment conducted with young and older listeners. The sound pressure levels of pure tones were varied at several signal-to-noise ratios to find a range of auditory signals that are audible and comfortably loud in noisy conditions. Ratings of the listeners were analyzed in terms of A- weighted sound pressure levels and 1/3 octave band levels of the target tones and background noises. The results revealed that both listener groups assigned similar ratings to various combinations of pure tones and domestic sounds. However, when the tone frequency was 2,000 Hz or higher, older listeners needed a higher tone level to attain a certain level of audibility. On the basis of the results, the authors propose sound-level ranges of auditory signals for consumer products intended for users of various ages and for users who might have age-related hearing loss. © 2010 The Acoustical Society of Japan.

Auditory signals are often used in human-machine interfaces of electric consumer products to inform the user of the state of operation. The signals are expected to enhance the usability of products, especially for older adults who are not accustomed to using such products. Kurakata et al. [Acoust. Sci. and Tech., 29, 176-184 (2008)] reported experimental results related to temporal patterns of auditory signals for electric home appliances on which a Japanese Industrial Standard (JIS S 0013:2002) was based. However, all participants in their experiment were residents of Japan. Therefore, it remains unclear whether the information that the auditory-signal patterns convey can be understood unambiguously by people in other countries who have different cultural backgrounds and who use products that have different interface designs from those sold on the Japanese market. This paper presents results of an experiment in which American, German, and Korean listeners participated and evaluated auditory signals, employing a similar procedure to that of the study by Kurakata et al. By comparing their judgments to those by Japanese listeners, internationally acceptable temporal patterns of auditory signals are proposed. ©2009 The Acoustical Society of Japan.

A re-examination of the hearing-threshold distribution is reported through statistical distribution method to show a more precise profile of auditory sensitivity at high frequencies. A mathematical transformation of threshold to improve the fitness of individual thresholds to a normal distribution is also proposed. Selected percentiles of threshold distribution that are estimated using the transformation are presented in a tabular and graphical form. It is found that for frequencies of 10 kHz and higher, the threshold distribution fits a normal distribution after a power-transformation of individual thresholds and is estimated more accurate. It is found that the percentile thresholds reported should be consulted for those frequencies when the hearing sensitivity of a person is examined in composition to the general population.

The hearing threshold for low frequency (LF) tones was measured in a pressure field to investigate the effects of ageing on hearing sensitivity. Participants were young adults around 20 years old and older adults over 60. Measurement results showed that the older listeners had a higher threshold, on average, than the young listeners. The difference of median thresholds between these two groups was about 10 dB at every measurement frequency. Furthermore, hearing abnormalities other than age-related hearing loss showed no great effect upon the LF thresholds. Comparison of LF thresholds and audiograms (i.e. mid and high frequency hearing) of the older listeners revealed only moderate correlation between them. These results suggest that older people retain good hearing sensitivity in the LF region, in contrast to their often-degraded sensitivity at higher frequencies. Therefore, in LF noise evaluation, we should carefully regard the possibility that older listeners can perceive a low level LF noise.

The statistical distribution of normal hearing thresholds for pure tones in the low-frequency (LF) region was estimated as a function of frequency, using a similar procedure to that used in an earlier work by the authors Kurakata et al., [3]. First, the distribution of individual LF thresholds was investigated using threshold measurement data. Results indicated that the threshold variation among individuals can be approximated using a normal distribution. Second, under the assumption of normality, standard deviations (SDs) of hearing threshold distributions were calculated. For that calculation, the measurement data of different studies were integrated to enhance the estimation accuracy. Finally, using the obtained SDs, the threshold distribution around the average value was presented graphically. These results illustrate the profile of our auditory sensitivity at LFs more accurately and are useful for evaluating the audibility of LF noises because they incorporate individual differences.

Consumer products that are currently available on the market, such as electric home appliances, often adopt auditory signals in their user interfaces. The signals are expected to improve the usability of such appliances for all users, including elderly people and visually impaired people. The Association for Electric Home Appliances (AEHA) established guidelines for auditory signals in 1999, which recommended temporal patterns of auditory signals for electric home appliances. The AEHA Guidelines were adopted later as a Japanese Industrial Standard (JIS S 0013:2002) without any major changes, but embracing a wider range of consumer products. For users, it is desirable that the specifications related to auditory signals in the standard be accepted widely internationally and that they be applied to every product. In this Technical Report, we translate and summarize the AEHA Report written in Japanese, on which the AEHA Guidelines and the JIS are based, in the hope that the JIS will become the foundation of an international standard on the auditory signals of consumer products. © 2008 The Acoustical Society of Japan.

Hearing thresholds for pure tones from 2 kHz to 28 kHz were measured. A 2AFC procedure combined with a 3-down 1-up transformed up-down method was employed to obtain threshold values that were less affected by listener's criterion of judgment. From some listeners, threshold values of 88 dB SPL or higher were obtained for a tone at 24 kHz, whereas thresholds could not be obtained from all participants at 26 kHz and above. Furthermore, thresholds were also measured under masking by a noise low-pass filtered at 20 kHz. At frequencies above 20 kHz, the difference of threshold values between with and without the masking noise was a few decibels, indicating that the tone detection was not affected by subharmonic components that might have appeared in the lower frequency regions. The results of measurement also showed that the threshold increased rather gradually for tones from 20 to 24 kHz whereas it increased sharply from 14 to 20 kHz.

Hearing sensitivity of otologically normal persons declines with their age. The pure-tone audiometric threshold of hearing of different age group of people is described. ISO 7029 reveals hearing sensitivity declines as a deviation from the threshold of 18-year-people. The average threshold value agreed well in this studies for young people of 20 years old and old people of 60 years old. In the physchoacoustic experiment the monaural air-condition threshold was measured with a pure-tone audiometer in a sound proof room excluding certain audiological abnormalities. The study confirms that people in recent years have a different auditory profile with better hearing ability at higher frequencies and the it is prominent particularly in case of males.

The ISO threshold values of different ages were reviewed. The ISO threshold values were compared with Japanese data published after the Robinson and Sutton survey. The results indicated that the Japanese people showed, on average, a smaller age-related decrease in hearing sensitivity than people did more than 30 years ago. The higher thresholds in the ISO standard seem to be influenced by noise-induced hearing loss, possibly because of noise exposure in the workplace.

The use of representative percentiles of normal hearing-threshold distribution in a tabular form are discussed. The researchers calculate the standard deviation (SD) of hearing thresholds as a function of frequency from 25Hz to 18Hz. Using the SDs and normative threshold values of the ISO standard, the normal threshold distribution profile could determine the entire range of audible frequencies. Thus it can be concluded that a table of representative values of threshold distributions can be more convenient to use than the mean and SD values.

The statistical distribution of normal hearing thresholds for pure tones of frontal incidence under binaural, free-field listening conditions was estimated as a function of frequency. First, the form of threshold distribution was investigated with threshold measurement data of the present study and those of other studies. Analytical results indicate that the threshold distribution has a form of normal distribution for the frequency range from 25 Hz to 16 kHz. Second, under the assumption of normality, standard deviations of thresholds were calculated for the frequency range from 25 Hz to 18 kHz by combining available threshold data of different studies. A supplementary experiment showed that thresholds at frequencies above 16 kHz were measurable with high reliability. These results illustrate the profile of our auditory sensitivity more accurately because they account for individual differences.

JIS S 0013, a guideline on auditory signals of consumer products, recommends ON/OFF temporal patterns to be used for auditory signals. In this guideline, ON/OFF patterns are determined according to the function of auditory signals, e. g. completion signals and attention signals. Therefore, when both completion and attention signal (s) are used, or more than one completion signal or attention signal is used in the same appliance, the following two problems arise: (1) the user of the appliance may not be able to distinguish among different auditory signals; and (2) the designer of the auditory signals has difficulty choosing the most appropriate signals from the recommended ones. To solve these problems, the authors conducted psychoacoustic experiments in which listeners judged dissimilarity and evaluated impressions of the auditory signals prescribed in the JIS. Based on the experimental results, the authors determined an attention signal that might be confused with completion signals and ON/OFF patterns of auditory signals to be selected when more than one signal is used in a single appliance.

Binaural hearing thresholds in free field were measured for pure tones to obtain threshold values in the high-frequency region. Measurement was conducted in an anechoic room of 4.35m (W) × 6.00m (D) × 2.95 m (H). Sound level deviations from the reference point met the sound field requirements of the preferred test conditions and more than ±1 dB were observed at 1 and 4kHz. The result illustrated the high-frequency region threshold curve.

The hitting sound of golf clubs with metal heads and of a club with a wood head were measured to investigate differences in their acoustic properties. Hitting was executed either by a swing machine or a human player. The results of analysis showed that the clubs with metal heads generated sounds around 100dB (L_{pA, Fmax}). This level was 5-15dB higher than that of the club with a wood head. The sounds of the metal-head clubs had relatively larger power in the high-frequency region of 4kHz and above compared to the wood-head club, which increased the overall levels. It would be desirable to develop a metal head with pleasant sound qualities, keeping the sound level lower in order to minimize damage to hearing.

The preferred volume levels of 16 television programs were investigated in psychoacoustic experiments with younger and older adults. The results revealed the following four points: (1) Older adults really tend to set the television volume louder than younger adults. (2) There is no significant difference in preferred volume levels between male and female subjects. (3) The preferred volume levels differ among television programs. This difference is not related to the contents of the programs, but rather their relative sound pressure levels when broadcast; Loud programs tended to be set to higher volume levels. (4) The preferred volume levels correlate significantly with the hearing levels of subjects. As the average hearing levels of seven frequencies from 125Hz to 8000Hz increase by 10dB, the preferred volume levels become higher by 3.4dB. These results might well serve as basic data to make indoor sound environments more comfortable for both young adults and senior citizens.

An experiment was conducted to study the interaction of the extrapolation mechanism with the effect of frequency proximity. The stimuli consisted of two sinusoidal glides with logarithmically changing frequency. Results show that when two gliding tones cross each other, they can create a crossing percept, as well as the bouncing percept. This effect could be observed when the glide durations were as short as 100 ms. The frequency changes of the glides were traced when they did not change in opposite directions, and a crossing perception could be elicited.

Performances of two skilled amateur pianists were analyzed to investigate factors deter mining the impression of the equality of intensity in piano music. The results of the analysis showed that although the pianists tried to play every tone as equally as possible, not all the tones were played in equal intensity. The following two features were found in the performances:(1) The pattern of fluctuation was regularly repeated throughout the performance.(2) The peak level of each "playing unit" was remarkably kept constant compared with the fluctuation of each tone. The same tendency was also found in the performances of professional pianists. The results of the psychoacoustical experiment showed that when these features were destroyed, the impression of equality was degraded. These findings suggest that skilled pianists can maintain the impression of the equality of intensity by making good use of the characteristics of our auditory perception.

The method for calculating loudness level proposed by Zwicker is standardized in ISO 532B. This is a graphical procedure and it can be tedious to calculate loudness level by this procedure. Recently, DIN 45631 has been revised including a computer program for calculating loudness level in BASIC which runs on IBM-compatible PC's. Since the NEC PC-9801 series computers are popular in Japan, the program has been modified for the NEC PC-9801 series computers and is introduced in this paper.

One of the most important concepts of accessible design is to increase users of products, services and environments to cover the widest range of human characteristics and capabilities. There are two possible methods on how to do it
one is to provide multiple means of information presentation or operation, and the other is to set design parameters of products etc., so that they accommodate diverse human characteristics and capabilities as much as possible. Both methods are addressed as basic strategies of accessible design to make products more accessible (i.e., used by more people). Conducting and repeating this step, products can reach an ideal goal of being universal. In this paper, the concept and methods of accessible design regarding the increase of users are discussed with some examples.

Purpose: It has long been common practice to design consumer products, living spaces, services, etc., with the assumption that the main users are healthy young people. However, when products are designed for older persons or persons with disabilities, the designers need to consider the sensory characteristics and abilities of these groups of users. The authors have constructed the 'Database of sensory characteristics of older persons and persons with disabilities'. Referring to the database will make it easier for designers to design products that accommodate various people who differ in their sensory characteristics and abilities&lt
sup&gt
1&lt
/sup&gt
. Method: The database displays sensory characteristics of vision, hearing, and touch measured at Advanced Industrial Science and Technology (AIST), Japan, by the authors from more than 3,000 young and older persons as well as persons with disabilities. These data for sensory characteristics have been adopted for establishing the Japanese Industrial Standards (JISs) 'Guidelines for older persons and persons with disabilities'. The database graphically presents the JIS contents described by equations and tables. Results &amp
Discussion Japanese and English versions of the database have been released on the web free of charge to the public (Figure 3). Anyone can access and use the data as long as they comply with the terms of use. In addition to contact information, the database has a questionnaire page to gather opinions and requests from users. Data released at this time are limited to 16 items, but the authors plan further expansion, including refinement of unreleased data and addition of new items in response to feedback from users through the questionnaires.

Autocorrelation function (ACF) parameters were used to identify low-frequency tonal sound detected in actual living environments. Five houses whose residents had made complaints for unidentified noise were selected as measurement sites. The sounds and the residents' detection responses were recorded simultaneously inside a room in each house. When they heard the suspected noise, the participants pushed a response button on a portable recording device as the sound was recorded. Results showed that tonal components in the low-frequency range were highly correlated with the sound detection. This study suggests that autocorrelation analysis can reveal the human detection of low-frequency tonal signals. Low-frequency tonal components were identified and quantified using ACF parameters: the delay time and amplitude of the ACFs first dominant peak. The amplitude was useful to describe the detection and prominence of low-frequency tonal components in noise. (C) 2011 Elsevier Ltd. All rights reserved.

This study investigated the relation between annoyance and single-number quantities to rate heavyweight floor impact sound insulation. Laboratory experiments were conducted to evaluate the subjective response of annoyance resulting from heavy-weight floor impact sounds recorded in wooden houses. Stimuli had two typical spectra and their modified versions, which simulate the precise change in frequency response resulting from insulation treatments. Results of the first experiment showed that the Zwicker's percentile loudness (N(5)) was the quantity to rate most well annoyance of heavy-weight impact sound over a wide sound level range. The second experiment revealed that arithmetic average (L(iFavg,Fmax)) of octave-band sound pressure levels measured using the time constant "fast" and Zwicker's percentile loudness (N(5)) much better described annoyance by the precise change in the sound spectrum attributable to insulation treatments than Japanese standardized single-number quantities (L(i,Fmax,r), L(iA,Fmax), and L(i,Fmax,Aw)) do. Japanese standardized single-number quantities using the A-weighting curve as a rating curve were found to be excessively influenced by the 63 Hz octave-band sound level and have the great sound level-dependences in the relation with subjective ratings. (C) 2011 Acoustical Society of America. [DOI:10.1121/1.3561660]

We have reported the results of recent survey of high-frequency sounds above 10 kHz radiated from the Japanese high speed (Shinkansen) and conventional railways, and the difference between impressions on the train noise with and without such high-frequency sounds, as interim report. From both the time-history and the frequency characteristics of wayside noise, the fact was re-acknowledged that the high-frequency sounds were radiated when a train traveled round a curved track and that they could be observed before the train passed by. The sound had dominant frequency components above 10 kHz and differed significantly in the frequency characteristics from common railway noises. And it was also noted that there was a large difference in the sound pressure levels measured by different sound level meters, mainly due to the frequency characteristics above 10 kHz of the microphones. Subjective impression was examined using the train noise with and without the high-frequency components. Seventeen participants aged between 17 and 58 judged the impression of the sounds using semantic differential. The results showed that high-frequency components had a great influence not only on the difference in sound pressure levels measured by different sound level meters as described above but also on the impression of participants younger than 20 years old. The high-frequency sounds above 10 kHz seem to increase the feelings of discomfort and annoyance for the young people who can hear such sounds. Copyright © (2011) by the Institute of Noise Control Engineering.

A study was conducted to examine the effect of multiplicity of frequency components on the audibility of tone presented against interfering noise. The measurement method was essentially identical to that of an earlier study, but triangle-wave tones were used instead as an example of complex tones. The background noise and the target tones were reproduced by a personal computer. They were amplified using a power amplifier and presented to the listener through a loudspeaker in a soundproof room. The listener's chair was set at a distance of 2.5m from the loudspeaker, while the frequency characteristic of the sound reproduction system was corrected to be substantially flat at the listener's position using an equalizer. All the listeners performed pure-tone audiometry and tympanometry and completed a questionnaire concerning hearing difficulties before participating in the experiment to confirm that they had normal hearing for their age.

The subjective ratings of heavy-weight floor impact sounds in wood frame construction were examined. Heavy-weight floor impact sounds were recorded in a mock-up building, which had four floors and two rooms each floor. The different insulation treatments were installed in the floors of each room and walls separating rooms. The stimuli consisted of 48 sounds (4 types × 2 receiver positions × 6 rooms) recorded in the mock-up building, which had 49-78 dB in the single number rating index (Lii,Fmax,r). Low pass filter with cutoff frequency 1.5 kHz was applied to remove electrical noise components in higher frequency range. The pink noise was produced from 8 loud speakers at every each 45 degree at the 1.75 m from subject and at the height of subject's ear positions. The results showed that sound insulations in higher frequency octave bands are more effective to decrease annoyance than those in lower frequency octave bands for the heavy-weight impact sound.

The impact source (tire in JIS 1418-2:2000) currently used to evaluate heavy-weight floor impact sound insulation seems to have too much impact force for the wood frame construction. Moreover, it is not well confirmed that what kind of impact source and physical index are reasonable to evaluate the insulation performance in the wood frame construction. This pilot study confirmed the relation between subjective ratings and physical indices of heavy-weight floor impact sound recorded by various impact sources in mock-up of wood frame construction. The recorded floor impact sound level showed that rubber ball sound at 10 cm showed similar sound level and spectrum to adult's jumping sound. The subjective tests found that LiFavg,Fmax (arithmetic means of octave band level, 63-1k Hz) was best correlated with annoyance. Floor impact sound with dominant spectral component in high frequency range showed larger annoyance. Result of this study suggests that weaker impact source is needed and higher frequency band should be given attention to physical rating index and reduction of annoyance by floor impact sound.

An on-site measurement system of low frequency noise (LFN) and annoyance response to lowfrequency noise was developed to find the reasons why people suffer from environmental noise with low frequency component. The advantage of this system is that we can easily find the relationship between complainants' subjective responses to acoustical events in dwellings and their physical properties such as time trend and frequency characteristics. Measurements were conducted with the developed system in residential houses and responses of complainants were also collected using a switch box during measurements. The system is capable to do FFT and 1/3 octave band analysis for five channels with enough frequency resolution. Four analysis channels were used for interior noise measurement and the rest was for outdoor measurement. Additional sound level meter with real-time 1/3 octave band analyzer was also used. Complainants were asked to operate switches when he/she detected the beginning and the end of the target noise during the measurement. This paper explains the developed system and an example of measurement result.

Auditory signals are often used in human-machine interface of consumer electronics. Those signals are expected to improve the usability and accessibility of such products. This paper reviews accessibility-related standards on auditory signals for consumer products that were established by the Japan Industrial Standards Committee and are being drafted in a Technical Committee of the International Organization for Standardization, ISO/TC 159 "Ergonomics". ©2009 IEEE.

A preliminary study reported the results of equal-loudness-level contours (ELLC) of older adults, which was measured by magnitude estimation (ME) method. The geometrical mean of the two numbers assigned to each stimulus was first calculated to obtain a magnitude estimate of individual listeners. ME method was produced ELLCs efficiently with precision comparable to those of other psychophysical methods, such as the method of constant stimuli and the bracketing method. The results of the study indicated that the ME method was able to yield ELLCs comparable to those in the ISO standard obtained with other measurement methods. ELLCs for numerous older adults were obtained in a short time using the ME method.

With the recent trend of decreased birthrate and increased aging population, design that can be used by as many people as possible including the elderly, or accessible design, has been incorporated in consumer product designs. The authors have developed and propagated accessible design technology through the establishment of Japanese Industrial Standard (JIS) based on auditory and visual functions of elderly people. This paper uses JIS S 0014, a standard for adjustment method of sound volume of auditory signals, to describe the research process that leads to the standardization of accessible design from the perspective of Full Research.

The hearing threshold for low-frequency tones of 10-160 Hz was measured in a pressure field to investigate the effects of aging on hearing sensitivity. Participants were young adults of 19-25 years old and older adults of 60 years and over. Measurement results showed that the older listeners had a higher threshold than the young listeners on average. However, the difference of median thresholds between these two groups was 5-10 dB at every measurement frequency, which was a much smaller difference than that observed for high-frequency tones around 2,000 Hz and above. Comparison of the low-frequency thresholds and audiograms of the listeners indicated almost no correlation between these two. These experimental results suggest that older people retain good hearing sensitivity in the low-frequency region compared to their degraded sensitivity at higher frequencies. The second report of the study presented at Low Frequency 2006 in Bristol, UK: the number of participants was increased.

A new Technical Report of Japanese Industrial Standard, JIS/TR S 0001, was made public in January 2002. This JIS/TR is a database for determining the acoustic properties of auditory signals used in consumer products
it consists of (1) graphical data of the frequency characteristics of domestic sounds, and (2) a library of recorded sounds on compact disc. The former can be used to graphically determine combinations of frequency and sound pressure level of auditory signals that are audible against domestic sounds. The latter is intended for use in a psychoacoustic experiment in which auditory signals are presented along with domestic sound(s) of the library
listeners are asked then to judge how they perceive the signals. The experiment can be carried out using either a loudspeaker or headphones. This JIS/TR will facilitate the development of suitable auditory signals for domestic appliances used under various noisy conditions and by a variety of users, including the elderly.

A series of experiments was conducted concerning the effect of amplitude-modulated (AM) sounds on the impression of broad-band noise. The following results were found:(1) AM sounds in broad-band noise were detected when S/N was around zero (S: the level of AM sound, N: 1/3 octave band level of broad-band noise with center frequency corresponding to the carrier frequency of AM sounds). Close examination showed that carrier frequency, modulation frequency and modulation depth had a systematic effect on the detection of AM sounds.(2) The loudness of broad-band noise mixed with AM sounds could be approximately evaluated by loudness level based on ISO 532B (LLz).(3) The timbre of broad-band noise mixed with AM sounds was judged to be more metallic as the carrier frequency of AM sounds became higher and to be more clamorous as the carrier frequency became lower. This suggests that the timbre is deteriorated when AM sounds are mixed with broad-band noise. The three factors were extracted by the factor analysis: they were "metallic" or "unpleasant, " "powerful" and "rough."