Adaptive Processes in Hearing.

Our auditory environment is constantly changing and evolving over time, requiring us to rapidly adapt to a complex dynamic sensory input. This adaptive ability of our auditory system can be observed at different levels, from individual cell responses to complex neural mechanisms and behavior, and is essential to achieve successful speech communication, correct orientation in our full environment, and eventually survival. These adaptive processes may differ in individuals with hearing loss, whose auditory system may cope via "readapting" itself over a longer time scale to the changes in sensory input induced by hearing impairment and the compensation provided by hearing devices.

Individual Hearing Loss: Characterization, Modelling, Compensation Strategies.

It is well-established that hearing loss does not only lead to a reduction of hearing sensitivity. Large individual differences are typically observed among listeners with hearing impairment in a wide range of suprathreshold auditory measures. In many cases, audiometric thresholds cannot fully account for such individual differences, which make it challenging to find adequate compensation strategies in hearing devices.

Hearing loss in relation to sound exposure of professional symphony orchestra musicians.

Objectives: The objectives of this study were to: (1) estimate the hearing status of classical symphony orchestra musicians and (2) investigate the hypothesis that occupational sound exposure of symphony orchestra musicians leads to elevated hearing thresholds.

Design: The study population comprised all the musicians from five symphony orchestras. Questionnaires were filled in by 337 subjects, and 212 subjects performed an audiometric test.

A user-operated audiometry method based on the maximum likelihood principle and the two-alternative forced-choice paradigm.

Objective: To create a user-operated pure-tone audiometry method based on the method of maximum likelihood (MML) and the two-alternative forced-choice (2AFC) paradigm with high test-retest reliability without the need of an external operator and with minimal influence of subjects' fluctuating response criteria. User-operated audiometry was developed as an alternative to traditional audiometry for research purposes among musicians.

Design: Test-retest reliability of the user-operated audiometry system was evaluated and the user-operated audiometry system was compared with traditional audiometry.

Reference hearing threshold levels for chirp signals delivered by an ER-3A insert earphone.

Objective: To establish reference hearing threshold levels for chirps and frequency-specific chirps.

Design: Hearing thresholds were determined monaurally for broad-band chirps and octave-band chirps using the Etymotic Research, ER-3A insert earphone. The chirps were presented using two repetition rates, 20 and 90 stimuli/s, and with alternating polarity in blocks of one second duration.

Sound exposure of symphony orchestra musicians.

Background: Assessment of sound exposure by noise dosimetry can be challenging especially when measuring the exposure of classical orchestra musicians where sound originate from many different instruments. A new measurement method of bilateral sound exposure of classical musicians was developed and used to characterize sound exposure of the left and right ear simultaneously in two different symphony orchestras.

Objectives: To measure binaural sound exposure of professional classical musicians and to identify possible exposure risk factors of specific musicians.

Free-field correction values for Interacoustics DD 45 supra-aural audiometric earphones.

Objective: This paper reports free-field correction values for the Interacoustics DD 45 audiometric earphone. The free-field correction values for earphones provide the loudness based equivalence to loudspeaker presentation. Correction values are especially used for the calibration of audiometric equipment for speech audiometry performed with headphones.

Equivalent threshold sound pressure levels (ETSPL) for Interacoustics DD 45 supra-aural audiometric earphones.

This paper describes the determination and results of pure-tone equivalent threshold sound pressure levels for the Interacoustics DD 45 audiometric earphone equipped with standard Model 51 cushions. The size and shape of the DD 45 transducer resembles the classic Telephonics TDH 39 earphone. Pure-tone hearing threshold measurements were performed for both ears of 29 test subjects.

Equivalent threshold sound pressure levels (ETSPL) for Sennheiser HDA 280 supra-aural audiometric earphones in the frequency range 125 Hz to 8000 Hz.

Hearing threshold sound pressure levels were measured for the Sennheiser HDA 280 audiometric earphone. Hearing thresholds were measured for 25 normal-hearing test subjects at the 11 audiometric test frequencies from 125 Hz to 8000 Hz. Sennheiser HDA 280 is a supra-aural earphone that may be seen as a substitute for the classical Telephonics TDH 39.

Reference hearing threshold levels for short duration signals.

Hearing thresholds for clicks and tonebursts were measured on 26 otologically normal persons (age 18-25 years) using the earphones Sennheiser HDA 200 and Telephonics TDH 39. The test signals are specified in IEC 60645-3 and in ISO 389-9. The acoustic test signals were presented both as a single stimulus and as repeated stimuli with the repetition rate of 20 Hz.

Questionnaire investigation of musicians' use of hearing protectors, self reported hearing disorders, and their experience of their working environment.

Musicians in symphony orchestras are exposed to harmful sound levels. Although research shows that industrial workers have a higher propensity to noise-induced hearing loss, musicians can also develop a hearing loss from noise exposure. Furthermore, musicians can suffer from tinnitus, hyperacusis, and distortion, among other hearing disorders, which can affect their work more severely than a hearing loss.

Hearing ability in Danish symphony orchestra musicians.

The audiograms of fifty-seven musicians from four Danish symphony orchestras were determined in connection with an interview about their working experience. Measurements of sound levels and noise dose were performed during rehearsal and during concerts in the four orchestras with the measurement equipment placed in various instrument groups. The average audiogram showed a decrease at higher frequencies similar to an age-related hearing loss.

Prediction of Intelligibility of Non-linearly Processed Speech.

Speech in various noise backgrounds was processed through four different non-linear devices and the intelligibility of the processed signals was predicted from the Speech Transmission Index (STI). A novel calculation method was applied in order to avoid artifacts. Running speech was used as input signal and STI was calculated from the envelopes of the squared, noise-free speech signal and of the processed, squared, noisy signal in 23 critical bands.