1,721,374 research outputs found
Predicting speech intelligibility in adverse conditions: evaluation of the speech-based envelope power spectrum model
Full text linkThe speech-based envelope power spectrum model (sEPSM) [Jørgensen and Dau (2011). J. Acoust. Soc. Am., 130 (3),1475–1487] estimates the envelope signal-to-noise ratio (SNRenv) of distorted speech and accuratelydescribes the speech recognition thresholds (SRT) for normal-hearing listeners in conditions with additive noise, reverberation, and nonlinearprocessing by spectral subtraction. The latter represents a condition where the standardized speech intelligibility index and speech transmission indexfail. However, the sEPSM is limited to stationary interferers due to the fact that predictions are based on the long-term SNRenv. As an attempt to extentthe model to deal with fluctuating interferers, a short-time version of the sEPSM is presented. The SNRenv of a speech sample is estimated from acombination of SNRenv-values calculated in short time frames. The model is evaluated in adverse conditions by comparing predictions to measured datafrom [Kjems et al. (2009). J. Acoust. Soc. Am. 126 (3), 1415-1426] where speech is mixed with four different interferers, including speech-shapednoise, bottle noise, car noise, and cafe noise. The model accounts well for the differences in intelligibility observed for the different interferers. Noneof the standardized models successfully describe these data
Monaural and binaural subjective modulation transfer functions in simple reverberation
No full textThe envelope of a signal is filtered by the transmission channel through which it passes. The amount of reduction for a given envelope, or modulation, frequency has been called the modulation transfer function (MTF) and can be derived from the impulse response of the transmission channel [Schroeder, M.R. (1981) Modulation transfer-functions: Definition and measurement, Acustica, 49, 179-182]. The envelope of a speech signal is critical for intelligibility, and the speech transmission index (STI) predicts the intelligibility of speech through a given transmission channel based on its MTF [Houtgast, T. and Steeneken, H.J.M. (1973) Modulation transfer-function in room acoustics as a predictor of speech intelligibility, Acustica, 28, 66-73]. In the present study, the results of intensity modulation detection experiments with broad-band noise carriers are reported in monaural and binaural conditions, with single reflections at different arrival times in the two ears and with a simulated room impulse response. The monaural data describe a subjective MTF, which is similar to the physical MTF. An interaural modulation phase difference can create an interaural intensity fluctuation, which can give a binaural advantage in detecting the intensity modulation. This binaural advantage could be used to enhance speech intelligibility over purely monaural listening
Individual cochlear delays estimated with otoacoustic emissions and auditory brainstem measurements
No full textOn the relationship between multi-channel envelope and temporal fine structure
Full text linkThe envelope of a signal is broadly defined as the slow changes in time of the signal, where as the temporal fine structure (TFS) are the fast changes in time, i.e. the carrier wave(s) of the signal. The focus of this paper is on envelope and TFS in multi-channel systems. We discuss the difference between a linear and a non-linear model of information-extraction from the envelope, and show that using a non-linear method for information-extraction, it is possible to obtain almost all information about the originating signal. This is shown mathematically and numerically for different kinds of systems providing an increasingly better approximation to the auditory system. A corollary from these results is that it is not possible to generate a test signal containing contradictory information in its multi-channel envelope and TFS
Interaural bimodal pitch matching with two-formant vowels
Full text linkFor bimodal patients, with a hearing aid (HA) in one ear and a cochlear implant (CI) in the opposite ear, usually a default frequency-to-electrode map is used in the CI. This assumes that the human brain can adapt to interaural place-pitch mismatches. This “one-size-fits-all” method might be partly responsible for the large variability of individual bimodal benefit. Therefore, knowledge about the location of the electrode array is an important prerequisite for optimum fitting. Theoretically, the electrode location can be determined from CT-scans. However, these are often not available in audiological practice. Behavioral pitch matching between the two ears has also been suggested, but has been shown to be tedious and unreliable. Here, an alternative method using two-formant vowels was developed and tested with a vocoder system simulating different CI insertion depths. The hypothesis was that patients may more easily identify vowels than perform a classical pitch-matching task. A spectral shift is inferred by comparing vowel spaces, measured by presenting the first formant in the HA and the second either in the HA or the CI. Preliminary results suggest that pitch mismatches can be derived from such vowel spaces. In order to take auditory adaptation in individual patients into account, the method will be tested with CI patients with contralateral residual hearing
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