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Loudness
Published in Stanley A. Gelfand, Hearing, 2017
The critical band concept was introduced with respect to masking in the last chapter. As we shall see, loudness also bears an intimate relationship to the critical bandwidth, and loudness experiments provide a direct estimate of the width of the critical band. As Scharf (1970) pointed out, it is convenient to think of the critical band as the bandwidth where abrupt changes occur. Consider the following experiment with this concept in mind.
ENTRIES A–Z
Published in Philip Winn, Dictionary of Biological Psychology, 2003
The extraction, categorization and grouping of sound features that allows the analysis of scenes into well segregated sources are the most important aspects of auditory perception. Hearing comprises a combination of an analysis stage in the COCHLEA and a central stage of synthesis. The analysis stage is characterized by frequency resolution, the capacity to project the components of complex sound on a frequency scale, by non-linear processing which allows the large dy-namic range and generates combination tones, and by lateral suppression providing contrast enhancement in the frequency domain. The ability to hear the myriad of combination tones when two tones are presented simultaneously (see OTOACOUSTIC EMISSIONS) relates to the essential non-linear nature of BASILAR MEMBRANE movement largely caused by the action of the outer hair cells (see HAIR CELLS). Most of the analysis capacities are attributable to cochlear frequency analysis (see AUDITORY TUNING CURVE). For instance the just-noticeable difference (jnd) for frequency is about 0.15% between 500 and 2000 Hz. The jnd for intensity discrimination drops from about 1.5 dB at near threshold levels to about 0.5 dB at levels of 80 dB above threshold. The critical band width, reflecting the perceptual frequency selectivity, is constant at about 150 Hz for frequencies below 1000 Hz and then increases proportional to frequency to become 1500 Hz at 10 kHz.
Hidden age-related hearing loss and hearing disorders: current knowledge and future directions
Published in Hearing, Balance and Communication, 2018
Richard Salvi, Dalian Ding, Haiyan Jiang, Guang-Di Chen, Antonio Greco, Senthilvelan Manohar, Wei Sun, Massimo Ralli
Ototoxic drugs preferentially damage the synapses of high thresholds type I neurons [26]. Although carboplatin damage to IHC and type I neurons in the chinchilla may not be identical to synaptopathy, insights into the perceptual deficits associated with synaptopathy might be gleaned from the hearing deficits observed in carboplatin-treated chinchilla. Moderate lesions confined to IHC and type I neurons have little effect on the audiogram measured in quiet (Figure 3(C)) [23]. However, the lesions had a profound effect on sound detection in the presence of noise. When thresholds were measured in broadband noise (BBN, 100–16,000 Hz) with an overall level of 50 dB SPL and a spectrum level of ∼7 dB/Hz, pre-carboplatin thresholds increased from approximately 30 dB at low frequencies to roughly 40 dB at 8–16 kHz (Figure 4) [31]. This is consistent with increase in the critical band with increasing frequency. After these baseline measures were obtained, chinchillas were treated with a dose of carboplatin that induced a moderate IHC lesion along the length of the cochlea. Post-carboplatin behavioural thresholds in BBN increased roughly 8–10 dB across the entire frequency range (Figure 4), consistent with the moderate loss of IHC along the length of the cochlea [31]. Thus, tone thresholds measured in BBN appears to be a sensitive technique to detect IHC/type I lesions in contrast to tone thresholds in quiet, which are insensitive to IHC/type I loss [31].
In-vivo characterisation of an implanted microphone and totally implantable active middle ear implant
Published in International Journal of Audiology, 2022
Bernd Waldmann, Tiago Rocha Félix, Mafalda Bento, Cristina Miranda, Maria Conceição Peixoto, Rui Pratas, Ruth English, Victor Correia da Silva
The individual microphone sensitivity was combined with knowledge about the electrical noise level of the microphone subsystem to calculate the input-referred noise level (in dB SPL) of the microphone. This in turn was converted to a masking level (in dB hearing level (dB HL) also known as dB normal sensation level (dB nSL), or dB effective masking level (dB EM), i.e. the level of the softest external acoustic test signal which the subject’s auditory pathway can distinguish from the noise. This conversion integrates the noise level over critical bands as defined in the literature (Zwicker and Terhardt, 1980).
Voice source, formant frequencies and vocal tract shape in overtone singing. A case study
Published in Logopedics Phoniatrics Vocology, 2023
Johan Sundberg, Björn Lindblom, Anna-Maria Hefele
The spectrum of a sustained vowel, whether sung or spoken, shows the amplitudes and frequencies of its harmonic partials. The frequency of the lowest partial fo, – the fundamental, – determines the pitch of the vowel. The frequencies of the other partials – the overtones – occur at multiples of the fo. Normally, they are not perceived individually. The spectral envelope determines the perceived vowel and voice quality. This is because our hearing system averages the spectral information in broad frequency bands – the critical bands of hearing.