Quality and loudness judgments for music subjected to compression limiting

Factors in the Effective Use of Hearing Aids among Subjects with Age-Related Hearing Loss: A Systematic Review

Objectives: Investigate factors contributing to the effective management of age-related hearing loss (ARHL) rehabilitation. Methods: A systematic review was conducted following PRISMA guidelines. The protocol was registered in PROSPERO (CRD42022374811). Articles were identified through systematic searches in the Scopus, PubMed, Web of Science, and Cochrane databases in May 2024. Only articles published between January 2005 and May 2024 were included. Studies were assessed for eligibility by two independent researchers and evaluated using the Crowe Critical Appraisal Tool v1.4 (CCAT). Results: Of the 278 articles identified, 54 were included. Three factors explain effective HA use. First, hearing aid signal processing, with directional microphones and noise reduction, improves user comfort and understanding regarding noise. Second, there is hearing aid fitting, with the NAL prescription rules as the gold standard, and bilateral, high-level HA performance for spatial localization and noise comprehension. Third, there is a patient-centered approach, using patient-related outcome measures (PROMs), questionnaires, counseling, and regular follow-up to involve patients in their therapeutic rehabilitation. Conclusions: Reaching a consensus on acoustic parameters is challenging due to variability in audiological results. Involving patients in their rehabilitation, addressing their needs and expectations, and offering individualized care are crucial.

Effect of Digital Noise Reduction of Hearing Aids on Music and Speech Perception

Background and Objectives

Although many studies have evaluated the effect of the digital noise reduction (DNR) algorithm of hearing aids (HAs) on speech recognition, there are few studies on the effect of DNR on music perception. Therefore, we aimed to evaluate the effect of DNR on music, in addition to speech perception, using objective and subjective measurements.

Subjects and Methods

Sixteen HA users participated in this study (58.00±10.44 years; 3 males and 13 females). The objective assessment of speech and music perception was based on the Korean version of the Clinical Assessment of Music Perception test and word and sentence recognition scores. Meanwhile, for the subjective assessment, the quality rating of speech and music as well as self-reported HA benefits were evaluated.

Results

There was no improvement conferred with DNR of HAs on the objective assessment tests of speech and music perception. The pitch discrimination at 262 Hz in the DNR-off condition was better than that in the unaided condition (p=0.024); however, the unaided condition and the DNR-on conditions did not differ. In the Korean music background questionnaire, responses regarding ease of communication were better in the DNR-on condition than in the DNR-off condition (p=0.029).

Conclusions

Speech and music perception or sound quality did not improve with the activation of DNR. However, DNR positively influenced the listener’s subjective listening comfort. The DNR-off condition in HAs may be beneficial for pitch discrimination at some frequencies.

Music Participation Among School-Aged Children Who Are Hard of Hearing

Purpose Music is an important part of life for many people. Furthermore, music training has been shown to improve a variety of cognitive functions among children and adults. However, little research exists on how children who are hard of hearing (HH) perceive or participate in music. In particular, it is unknown whether hearing loss limits participation in music activities among school-aged children with mild-to-severe hearing loss. The purpose of this study was to determine whether hearing loss limits participation among children who are HH compared to children with normal hearing (NH). Method Participants were parents of 2 cohorts of children finishing 5th grade (approximately 11 years old). Parents were asked to complete a survey (online or paper) regarding the role of music in their child's life. A total of 88 surveys were completed (67 from parents of children who are HH and 21 from parents of children with NH, with an overall response rate of 74%). Results Hearing loss did not limit music participation among children. Children who are HH listened to recorded music, attended live concerts, and practiced an instrument at the same rates as children with NH. Listening to recorded and live music, practicing an instrument, and playing in an ensemble were equally as important to children who are HH as children with NH. Children who are HH were significantly more likely to regularly play in an ensemble than children with NH. Parent participation in music significantly influenced music participation for children who are HH but not children with NH. Descriptive data about music genres, instruments, and ensembles are also presented. Conclusions Children who are HH participate in music at the same or greater rates as children with NH. Parent participation in music may be particularly important for children who are HH. In light of this, music listening should be a consideration when fitting children with hearing aids.

Increased levels of bass in popular music recordings 1955-2016 and their relation to loudness

The sound of recorded music has changed over time. These changes can be captured by different audio features. Over the past decades, popular songs have shown clear increases in RMS energy and loudness, but far less attention has addressed whether this upward trend is more prevalent in specific frequency bands, such as the bass. Bass frequencies are especially important for movement induction, such as foot tapping or dancing, and might offer competitive advantages of capturing attention and increasing engagement. Here, the authors examined the evolution of audio features, such as root-mean-square (RMS) energy, loudness, and spectral fluctuations (changes in the audio signal's frequency content) in ten frequency bands from songs on the Billboard Hot 100 charts from 1955 to 2016. Over time, RMS energy and loudness increased while dynamic range decreased. The largest increases were found in the bass range: Spectral flux increased most strongly in the lowest frequency bands (0-100 Hz), and when controlling for overall RMS, only the lowest frequency bands showed an increase over time. The upward trend of bass could reflect changes in technology and style; but based on links between bass and movement, it is likely a widespread technique to increase engagement and contribute to chart success.

Validation of clinical techniques for verification of uniform attenuation earplugs

OBJECTIVE

Uniform attenuation earplugs (UAE) theoretically provide near even attenuation across frequencies when built to a manufacturer's specifications. Unfortunately, there is no current research available confirming if custom-molded uniform attenuation earplugs (UAE) are made to specifications nor is there guidance available on clinical methods of measuring attenuation of uniform attenuation earplug (UAE) devices. The goal of this study was to evaluate different procedures for UAE verification and to determine the most accurate clinically accessible verification protocol.

DESIGN

Attenuation was measured using probe microphone techniques, as well as real-ear attenuation at threshold (REAT) measurements under circumaural earphones, soundfield speakers and supra-aural earphones. Comparisons were made to a reference system created in the laboratory.

STUDY SAMPLE

Seventeen adult participants, totaling 30 ears.

RESULTS

The results of this study demonstrate that the REAT measured in the soundfield using a narrowband noise stimulus with masking in the contralateral ear is currently the most accurate and widely available method of verifying UAEs.

CONCLUSIONS

Factoring in clinical efficiency, the authors of this study recommend verifying attenuation levels using a soundfield REAT procedure as best clinical practice. In addition, the data suggests that REAT measurements under circumaural earphones are an acceptable second choice method.

Chosen Listening Levels for Music With and Without the Use of Hearing Aids

PURPOSE

The objective of this study was to describe chosen listening levels (CLLs) for recorded music for listeners with hearing loss in aided and unaided conditions.

METHOD

The study used a within-subject, repeated-measures design with 13 adult hearing-aid users. The music included rock and classical samples with different amounts of audio-industry compression limiting. CLL measurements were taken at ear level (i.e., at input to the hearing aid) and at the tympanic membrane.

RESULTS

For aided listening, average CLLs were 69.3 dBA at the input to the hearing aid and 80.3 dBA at the tympanic membrane. For unaided listening, average CLLs were 76.9 dBA at the entrance to the ear canal and 77.1 dBA at the tympanic membrane. Although wide intersubject variability was observed, CLLs were not associated with audiometric thresholds. CLLs for rock music were higher than for classical music at the tympanic membrane, but no differences were observed between genres for ear-level CLLs. The amount of audio-industry compression had no significant effect on CLLs.

CONCLUSION

By describing the levels of recorded music chosen by hearing-aid users, this study provides a basis for ecologically valid testing conditions in clinical and laboratory settings.

Dynamic Range Across Music Genres and the Perception of Dynamic Compression in Hearing-Impaired Listeners

Dynamic range compression serves different purposes in the music and hearing-aid industries. In the music industry, it is used to make music louder and more attractive to normal-hearing listeners. In the hearing-aid industry, it is used to map the variable dynamic range of acoustic signals to the reduced dynamic range of hearing-impaired listeners. Hence, hearing-aided listeners will typically receive a dual dose of compression when listening to recorded music. The present study involved an acoustic analysis of dynamic range across a cross section of recorded music as well as a perceptual study comparing the efficacy of different compression schemes. The acoustic analysis revealed that the dynamic range of samples from popular genres, such as rock or rap, was generally smaller than the dynamic range of samples from classical genres, such as opera and orchestra. By comparison, the dynamic range of speech, based on recordings of monologues in quiet, was larger than the dynamic range of all music genres tested. The perceptual study compared the effect of the prescription rule NAL-NL2 with a semicompressive and a linear scheme. Music subjected to linear processing had the highest ratings for dynamics and quality, followed by the semicompressive and the NAL-NL2 setting. These findings advise against NAL-NL2 as a prescription rule for recorded music and recommend linear settings.

The Dynamic Range for Korean Standard Sentence Material: A Gender Comparison in a Male and a Female Speakers

Background and Objectives

The purpose of this study was to identify differences between the dynamic ranges (DRs) of male and female speakers using Korean standard sentence material. Consideration was especially given to effects within the predefined segmentalized frequency-bands.

Materials and Methods

We used Korean standard sentence lists for adults as stimuli. Each sentence was normalized to a root-mean-square of 65 dB sound pressure level. The sentences were then modified to ensure there were no pauses, and the modified sentences were passed through a filter bank in order to perform the frequency analysis. Finally, the DR was quantified using a histogram that showed the cumulative envelope distribution levels of the speech in each frequency band.

Results

In DRs that were averaged across all frequency bands, there were no significant differences between the male and the female speakers. However, when considering effects within the predefined frequency bands, there were significant differences in several frequency bands between the DRs of male speech and those of female speech.

Conclusions

This study shows that the DR of speech for the male speaker differed from the female speaker in nine frequency bands among 21 frequency bands. These observed differences suggest that a standardized DR of male speech in the band-audibility function of the speech intelligibility index may differ from that of female speech derived in the same way. Further studies are required to derive standardized DRs for Korean speakers.

Music and hearing aids

The signal processing and fitting methods used for hearing aids have mainly been designed to optimize the intelligibility of speech. Little attention has been paid to the effectiveness of hearing aids for listening to music. Perhaps as a consequence, many hearing-aid users complain that they are not satisfied with their hearing aids when listening to music. This issue inspired the Internet-based survey presented here. The survey was designed to identify the nature and prevalence of problems associated with listening to live and reproduced music with hearing aids. Responses from 523 hearing-aid users to 21 multiple-choice questions are presented and analyzed, and the relationships between responses to questions regarding music and questions concerned with information about the respondents, their hearing aids, and their hearing loss are described. Large proportions of the respondents reported that they found their hearing aids to be helpful for listening to both live and reproduced music, although less so for the former. The survey also identified problems such as distortion, acoustic feedback, insufficient or excessive gain, unbalanced frequency response, and reduced tone quality. The results indicate that the enjoyment of listening to music with hearing aids could be improved by an increase of the input and output dynamic range, extension of the low-frequency response, and improvement of feedback cancellation and automatic gain control systems.

Beyond Intensity: Spectral Features Effectively Predict Music-Induced Subjective Arousal

Emotions in music are conveyed by a variety of acoustic cues. Notably, the positive association between sound intensity and arousal has particular biological relevance. However, although amplitude normalization is a common procedure used to control for intensity in music psychology research, direct comparisons between emotional ratings of original and amplitude-normalized musical excerpts are lacking.

In this study, 30 nonmusicians retrospectively rated the subjective arousal and pleasantness induced by 84 six-second classical music excerpts, and an additional 30 nonmusicians rated the same excerpts normalized for amplitude. Following the cue-redundancy and Brunswik lens models of acoustic communication, we hypothesized that arousal and pleasantness ratings would be similar for both versions of the excerpts, and that arousal could be predicted effectively by other acoustic cues besides intensity.

Although the difference in mean arousal and pleasantness ratings between original and amplitude-normalized excerpts correlated significantly with the amplitude adjustment, ratings for both sets of excerpts were highly correlated and shared a similar range of values, thus validating the use of amplitude normalization in music emotion research. Two acoustic parameters, spectral flux and spectral entropy, accounted for 65% of the variance in arousal ratings for both sets, indicating that spectral features can effectively predict arousal. Additionally, we confirmed that amplitude-normalized excerpts were adequately matched for loudness. Overall, the results corroborate our hypotheses and support the cue-redundancy and Brunswik lens models.

Effects of compression and onset/offset asynchronies on the detection of one tone in the presence of another

The weaker of two temporally overlapping complex tones can be easier to hear when the tones are asynchronous than when they are synchronous. This study explored how the use of fast and slow five-channel amplitude compression, as might be used in hearing aids, affected the ability to use onset and offset asynchronies to detect one (signal) complex tone when another (masking) complex tone was presented almost simultaneously. A 2:1 compression ratio was used with normal-hearing subjects, and individual compression ratios and gains recommended by the CAM2 hearing aid fitting method were used for hearing-impaired subjects. When the signal started before the masker, there was a benefit of compression for both normal-hearing and hearing-impaired subjects. When the signal finished after the masker, there was a benefit of fast compression for the normal-hearing subjects but no benefit for most of the hearing-impaired subjects, except when the offset asynchrony was relatively large (100 ms). The benefit of compression probably occurred because the compression improved the effective signal-to-masker ratio, hence reducing backward and forward masking. This apparently outweighed potential deleterious effects of distortions in envelope shape and the introduction of partially correlated envelopes of the signal and masker.

Analog-to-digital conversion to accommodate the dynamics of live music in hearing instruments

Hearing instrument design focuses on the amplification of speech to reduce the negative effects of hearing loss. Many amateur and professional musicians, along with music enthusiasts, also require their hearing instruments to perform well when listening to the frequent, high amplitude peaks of live music. One limitation, in most current digital hearing instruments with 16-bit analog-to-digital (A/D) converters, is that the compressor before the A/D conversion is limited to 95 dB (SPL) or less at the input. This is more than adequate for the dynamic range of speech; however, this does not accommodate the amplitude peaks present in live music. The hearing instrument input compression system can be adjusted to accommodate for the amplitudes present in music that would otherwise be compressed before the A/D converter in the hearing instrument. The methodology behind this technological approach will be presented along with measurements to demonstrate its effectiveness.