Informational masking in young and elderly listeners for speech masked by simultaneous speech and noise

Three experiments measured the effects of age on informational masking of speech by competing speech. The experiments were designed to minimize the energetic contributions of the competing speech so that informational masking could be measured with no large corrections for energetic masking. Experiment 1 used a "speech-in-speech-in-noise" design, in which the competing speech was presented in noise at a signal-to-noise ratio (SNR) of -4 dB. This ensured that the noise primarily contributed the energetic masking but the competing speech contributed the informational masking. Equal amounts of informational masking (3 dB) were observed for young and elderly listeners, although less was found for hearing-impaired listeners. Experiment 2 tested a range of SNRs in this design and showed that informational masking increased with SNR up to about an SNR of -4 dB, but decreased thereafter. Experiment 3 further reduced the energetic contribution of the competing speech by filtering it into different frequency bands from the target speech. The elderly listeners again showed approximately the same amount of informational masking (4-5 dB), although some elderly listeners had particular difficulty understanding these stimuli in any condition. On the whole, these results suggest that young and elderly listeners were equally susceptible to informational masking. © 2009 Acoustical Society of America.

Political Liberalism, Free Speech and Public Reason

In this paper, I critically assess John Rawls' repeated claim that the duty of civility is only a moral duty and should not be enforced by law. In the first part of the paper, I examine and reject the view that Rawls' position may be due to the practical difficulties that the legal enforcement of the duty of civility might entail. I thus claim that Rawls' position must be driven by deeper normative reasons grounded in a conception of free speech. In the second part of the paper, I therefore examine various arguments for free speech and critically assess whether they are consistent with Rawls' political liberalism. I first focus on the arguments from truth and self-fulfilment. Both arguments, I argue, rely on comprehensive doctrines and therefore cannot provide a freestanding political justification for free speech. Freedom of speech, I claim, can be justified instead on the basis of Rawls' political conception of the person and of the two moral powers. However, Rawls' wide view of public reason already allows scope for the kind of free speech necessary for the exercise of the two moral powers and therefore cannot explain Rawls' opposition to the legal enforcement of the duty of civility. Such opposition, I claim, can only be explained on the basis of a defence of unconstrained freedom of speech grounded in the ideas of democracy and political legitimacy. Yet, I conclude, while public reason and the duty of civility are essential to political liberalism, unconstrained freedom of speech is not. Rawls and political liberals could therefore renounce unconstrained freedom of speech, and endorse the legal enforcement of the duty of civility, while remaining faithful to political liberalism.

Insults, free speech and offensiveness

This article examines what is wrong with some expressive acts, ‘insults’. Their putative wrongfulness is distinguished from the causing of indirect harms, aggregated harms, contextual harms, and damaging misrepresentations. The article clarifies what insults are, making use of work by Neu and Austin, and argues that their wrongfulness cannot lie in the hurt that is caused to those at whom such acts are directed. Rather it must lie in what they seek to do, namely to denigrate the other. The causing of offence is at most evidence that an insult has been communicated; it is not independent grounds of proscription or constraint. The victim of an insult may know that she has been insulted but not accept or agree with the insult, and thereby submit to the insulter. Hence insults need not, as Waldron argues they do, occasion dignitary harms. They do not of themselves subvert their victims' equal moral status. The claim that hateful speech endorses inequality should not be conflated with a claim that such speech directly subverts equality.

Thus, ‘wounding words’ should not unduly trouble the liberal defender of free speech either on the grounds of preventing offence or on those of avoiding dignitary harms.

Individual differences in speech and language ability profiles in areas of high deprivation

Speech and language ability is not a unitary concept; rather, it is made up of multiple abilities such as grammar, articulation and vocabulary. Young children from socio-economically deprived areas are more likely to experience language difficulties than those living in more affluent areas. However, less is known about individual differences in language difficulties amongst young children from socio-economically deprived backgrounds. The present research examined 172 four-year-old children from socio-economically deprived areas on standardised measures of core language, receptive vocabulary, articulation, information conveyed and grammar. Of the total sample, 26% had difficulty in at least one area of language. While most children with speech and language difficulty had generally low performance in all areas, around one in 10 displayed more uneven language abilities. For example, some children had generally good speech and language ability, but had specific difficulty with grammar. In such cases their difficulty is masked somewhat by good overall performance on language tests but they could still benefit from intervention in a specific area. The analysis also identified a number of typically achieving children who were identified as having borderline speech and language difficulty and should be closely monitored

Freedom of Expression and Hate Speech

This is a study of free speech and hate speech with reference to the international standards and to the United States jurisprudence. The study, in a comparative and critical fashion, depicts the historical evolution and the application of the concept of ‘free speech,’ within the context of ‘hate speech.’ The main question of this article is how free speech can be discerned from hate speech, and whether the latter should be restricted. To this end, it examines the regulation of free speech under the First Amendment to the United States Constitution, and in light of the international standards, particularly under the International Convention on the Elimination of All Forms of Racial Discrimination, International Covenant on Civil and Political Rights, and the European Convention on Human Rights and Fundamental Freedoms. The study not only illustrates how elusive the endeavour of striking a balance between free speech and other vital interests could be, but also discusses whether and how hate speech should be eliminated within the ‘marketplace of ideas.’

Combining multi-band and frequency-filtering techniques for speech recognition in noisy environments

While current speech recognisers give acceptable performance in carefully controlled environments, their performance degrades rapidly when they are applied in more realistic situations. Generally, the environmental noise may be classified into two classes: the wide-band noise and narrow band noise. While the multi-band model has been shown to be capable of dealing with speech corrupted by narrow-band noise, it is ineffective for wide-band noise. In this paper, we suggest a combination of the frequency-filtering technique with the probabilistic union model in the multi-band approach. The new system has been tested on the TIDIGITS database, corrupted by white noise, noise collected from a railway station, and narrow-band noise, respectively. The results have shown that this approach is capable of dealing with noise of narrow-band or wide-band characteristics, assuming no knowledge about the noisy environment.

Robust bimodal person identification using face and speech with limited training data and corruption of both modalities

This paper presents a novel method of audio-visual fusion for person identification where both the speech and facial modalities may be corrupted, and there is a lack of prior knowledge about the corruption. Furthermore, we assume there is a limited amount of training data for each modality (e.g., a short training speech segment and a single training facial image for each person). A new representation and a modified cosine similarity are introduced for combining and comparing bimodal features with limited training data as well as vastly differing data rates and feature sizes. Optimal feature selection and multicondition training are used to reduce the mismatch between training and testing, thereby making the system robust to unknown bimodal corruption. Experiments have been carried out on a bimodal data set created from the SPIDRE and AR databases with variable noise corruption of speech and occlusion in the face images. The new method has demonstrated improved recognition accuracy.

Perception of Filtered Speech by Children with Developmental Dyslexia and Children with Specific Language Impairments

Here we use two filtered speech tasks to investigate children’s processing of slow (<4 Hz) versus faster (∼33 Hz) temporal modulations in speech. We compare groups of children with either developmental dyslexia (Experiment 1) or speech and language impairments (SLIs, Experiment 2) to groups of typically-developing (TD) children age-matched to each disorder group. Ten nursery rhymes were filtered so that their modulation frequencies were either low-pass filtered (<4 Hz) or band-pass filtered (22 – 40 Hz). Recognition of the filtered nursery rhymes was tested in a picture recognition multiple choice paradigm. Children with dyslexia aged 10 years showed equivalent recognition overall to TD controls for both the low-pass and band-pass filtered stimuli, but showed significantly impaired acoustic learning during the experiment from low-pass filtered targets. Children with oral SLIs aged 9 years showed significantly poorer recognition of band pass filtered targets compared to their TD controls, and showed comparable acoustic learning effects to TD children during the experiment. The SLI samples were also divided into children with and without phonological difficulties. The children with both SLI and phonological difficulties were impaired in recognizing both kinds of filtered speech. These data are suggestive of impaired temporal sampling of the speech signal at different modulation rates by children with different kinds of developmental language disorder. Both SLI and dyslexic samples showed impaired discrimination of amplitude rise times. Implications of these findings for a temporal sampling framework for understanding developmental language disorders are discussed.