Instrumental measures of speech intelligibility typically produce an index between 0 and 1 that is monotonically related to listening test scores. Binaural extensions of these measures have been proposed in the literature, essentially consisting of a binaural preprocessing stage followed by monaural intelligibility prediction using the better ear or the binaurally. Coherence and the speech intelligibility index scitation. In speech communication, intelligibility is a measure of how comprehensible speech is in given conditions. Index termscoherence function, coherent noise, microphone array, noise reduction. Improving objective intelligibility prediction by combining. Kates and arehart 3 proposed a hearingaid speech perception index haspi for hearing impaired hi and normal hearing nh listeners that was an extension of the threelevel coherence speech intelligibility index csii 4. Compare your calculated intelligibility level to the general expectations shown below in table 1 to determine if further evaluation is necessary. Using the coherence based function, noise is suppressed along with distortion in speech 3. The predicted speech reception threshold matches the pattern of the measured datawell, even though the predicted intelligibility. The ai can be expressed as a function of the masking level represented by the snr snr f in each frequency channel as ai f f 1 wf. Speech intelligibility index sii highenergy glimpse proportion metric coherence and speech intelligibility index csii quasistationary speech transmission index qsti shorttime objective intelligibility measure stoi extended stoi measure estoi hearingaid speech perception index haspi knearest neighbor mutual information. Evaluating the predictions of objective intelligibility. Introduction the aim of this work is to examine how well objective measures of speech quality and speech intelligibility can predict the intelligibility of speech that has undergone modi.
Although drafts of the standard were around in the mid1990s, it wasnt until the revision of the ansi s3. Coherence and the speech intelligibility index james m. An improved speech transmission index for intelligibility. Intelligibility is affected by the level loud but not too loud and quality of the speech signal, the type and level of background noise, reverberation some reflections but not too many, and, for speech over communication devices, the properties of the communication system. In combination with the coherence based speech intelligibility index, the model is applied to predict the speech intelligibility data measured by marrone et al. Coherencebased dualchannel noise reduction algorithm in a. Noise dependent super gaussiancoherence based dual. The articulation index ai, speechtransmission index sti, and coherencebased intelligibility metrics have been evaluated primarily in steadystate noisy. In writing, it is provided by a clear and understood structuring of paragraphs and sentences in writing. Introduction speech quality and intelligibility can be severely degraded in noisy or highly reverberant environments. Correlation and coherence based intelligibility measures. Katesa gn resound and university of colorado, department of speech language and hearing sciences. Predicting speech intelligibility using a gammachirp envelope.
As such, it neglects any other distortions caused by the enhancement procedure which also reduce the intelligibility of speech. The resulting snrs are then used as input for the speech intelligibility index sii. The absolute measurement of speech intelligibility is a complex science. The site provides software for calculating the speech intelligibility index sii, as well as notes relevant to potential future changes of the standard and the listing of known errors to be corrected in the next version of the standard. The solid line in each panel indicates the average aided sii values for children aged birth to 6 years. Coherence is one of the two qualities that give a written or spoken text unity and purpose. The articulation index ai, speechtransmission index sti, and coherencebased intelligibility metrics have been evaluated primarily in steadystate noisy conditions and have not been tested extensively in. Many algorithms for predicting the intelligibility of a communication system have been proposed. This presentation introduces a new intelligibility and sound.
Administration of the intelligibility in context scale. The sii involves measuring the signaltonoise ratio snr in separate frequency bands, modifying the estimated noise levels to include auditory masking, and computing a weighted sum across frequency of the modified snr values. An evaluation of intrusive instrumental intelligibility metrics arxiv. This presentation introduces a new intelligibility and soundquality calculation procedure based on the speech intelligibility index ansi s3. Objective measures for predicting speech intelligibility in. The sii concept for estimating intelligibility is extended in this paper to include broadband peakclipping and centerclipping distortion, with the coherence between the input and output signals used to estimate.
In this paper, we propose a new instrumental intelligibility metric that describes speech intelligibility using bits. Both the coherence based and stibased measures have been found to be good measures for modeling the intelligibility of vocoded speech. Objective measures for predicting speech intelligibility in noisy. Two frequently used objective measures are the sti speech transmission index, steeneken and houtgast, 1980, 1998, and the sii speech intelligibility index. The speech intelligibility index, or sii, is a measure, ranging between 0. Based on this, a gain function is defined to filter the noisy speech 10. The proposed ndr method provides a distance measure focused on a very specific type of distortion. Coherence and the speech intelligibility index nasaads. Warnes consulting november 18, 2018 this document describes the calculation of speech intelligibility index sii using r. Although drafts of the standard were around in the mid1990s, it wasnt until the revision of the.
Objective measures for predicting the intelligibility of. The sti measures some physical characteristics of a transmission channel a room, electroacoustic equipment, telephone line, etc. One type of quantitative test used to measure speech intelligibility is called speech transmission index public. Two objective intelligibility predictors are applied before and after processing. The most effective procedure divides the speech signal into low, mid, and highlevel regions, computes the coherence sii separately for the signal segments in each region, and then estimates intelligibility from a weighted combination of the three coherence sii values. Calculating speech intelligibility index sii using r. Calculating speech intelligibility index sii using r gregory r. Pdf coherence and the speech intelligibility index researchgate. A testing system for speech intelligibility in a noisy environment was developed and as a first. The objective rating of speech intelligibility by speech transmission index, 1998 isotr 4870 acoustics the construction and calibration of speech intelligibility tests, 1991 no reference given ansi s 3. The sii concept for estimating intelligibility is extended in this paper to include broadband peakclipping. To determine whether or not a childs level of speech intelligibility is ageappropriate, clinicians will often refer to the general guidelines that. Trends in hearing a binaural grouping model for the authors. The new index, the hearing aid speech perception index haspi, uses an auditory model that incorporates aspects of normal and impaired peripheral auditory function kates, 20.
The result of the analysis is an index that ranges from 0. Steinberg, 1947 and the speech intelligibility index sii ansi, 1997, were based on the assumption that the intelligibility of speech is given by the sum of the contributions to intelligibility within individual frequency bands french and steinberg, 1947. Aided speech intelligibility index sii normative values v1. The articulation index ai, speech transmission index sti, and coherence based intelligibility metrics have been evaluated primarily in steadystate noisy conditions and have not been tested extensively in fluctuating noise conditions. Request pdf coherence and the speech intelligibility index noise and distortion reduce the sound quality in hearing aids, but there is no established. Plot the aided sii value associated with speech input on panel b relative to the corresponding pta on the xaxis. Binaural speech intelligibility prediction and nonlinear. An improved speech processing strategy for cochlear implants. The core calculations have been encapsulated as an r addon package named\sii, which, once installed, can be loaded thusly. As such, these measures are dimensionless and do not represent physical quantities. The resulting sii is transformed into an intelligibility value using a nonlinear transform derived from a mapping function for sentence intelligibility. Most speech intelligibility metrics make use of the concept of signal. Introduction o ne of the most common complaints made by hearing impaired listeners is reduced speech intelligibility in noisy environments. Coherence refers to the general sense that a text makes sense through the organisation of its content.
The first method is the shorttime objective intelligibility stoi measure and the second measure is the coherence speech intelligibility index csii. Coherence and the speech intelligibility index request pdf. Administration of the intelligibility in context scale ics. The sti is a measure that is based on the generation and analysis of an artificial test signal that replaces the speech signal. The auditory coherence is computed from the modeled basilarmembrane vibration output in each frequency band, and provides a measurement sensitive to the changes in. Speech intelligibility index sii sii ai and ai share a common underlying idea. Speech intelligibility testing is a method used to determine if an emergency communication system ecs also called mass notification system, mns is clear, precise, and audible or intelligible.