Mark Haggard

''Sparse'' Temporal Sampling in Auditory fMRI

The use of functional magnetic resonance imaging (fMRI) to explore central auditory function may be compromised by the intense bursts of stray acoustic noise produced by the scanner whenever the magnetic resonance signal is read out. We present results evaluating the use of one method to reduce the effect of the scanner noise: “sparse” temporal sampling. Using this technique, single volumes of brain images are acquired at the end of stimulus and baseline conditions. To optimize detection of the activation, images are taken near to the maxima and minima of the hemodynamic response during the experimental cycle. Thus, the effective auditory stimulus for the activation is not masked by the scanner noise.

On the dissociation of spectral and temporal cues to the voicing distinction in initial stop consonants

It has been claimed that a rising first‐formant (F1) transition is an important cue to the voiced–voiceless distinction for syllable‐initial, prestressed stop consonants in English. Lisker [J. Acoust. Soc. Am. 57, 1547–1551 (L) (1975)] has pointed out that the acoustic manipulations suggesting a role for F1 have involved covariation of the onset frequency of F1 with the duration, and hence the frequency extent, of the F1 transition; he has argued that effects hitherto ascribed to the transition are more properly attributed to its onset. Two experiments are reported in which F1 onset frequency and F1 transition duration/extent were manipulated independently. The results confirm Lisker’s suggestion that the major effect of F1 in initial voicing contrasts is determined by its perceived frequency at the onset of voicing and show that a periodically excited F1 transition is not, per se, a positive cue to voicing. In further experiments, the relative levels and the frequencies at the onset of voicing of both F1...

Pitch as a Voicing Cue

The pitch change at the onset of voicing after a period of articulatory closure for a consonant reflects the state of the glottis during that closure. In initial position, a low rising pitch indicates a closed glottis and high falling pitch a glottis that is still partly open. An experiment is reported which shows that, for about 90% of the subjects, this pitch change in the vowel can cue the voiced/voiceless distinction for a preceding stop consonant in English. Control conditions suggest that this cue depends not upon low‐frequency energy content, but upon the pitch sensation.

Modulation and task effects in auditory processing measured using fMRI

Active listening has been reported to elicit a different sensory response from passive listening and is generally observed as an increase in the magnitude of activation. Sensory activation differences may therefore be masked by the effect of attention. The present study measured activation induced by static and modulated tones, while controlling attention by using target‐discrimination and passive listening tasks. The factorial design enabled us to determine whether the stimulus‐induced activation in auditory cortex was independent of the information‐processing demands of the task. Contrasted against a silent baseline, listening to the tones induced widespread activation in the temporal cortex, including Heschls gyrus (HG), planum temporale, superior temporal gyrus (STG), and superior temporal sulcus. No additional auditory areas were recruited in the response to modulated tones compared to static tones, but there was an increase in the response in the STG, anterior to HG. Relative to passive listening, the active task increased the response in the STG, posterior to HG. The active task also recruited regions in the frontal and parietal cortex and subcortical areas. These findings indicate that preferential responses to the changing spectro‐temporal properties of the stimuli and to the target‐discrimination task involve distinct, non‐overlapping areas of the secondary auditory cortex. Thus, in the present study, differences in sensory activation were not masked by the effects of attention. Hum. Brain Mapping 10:107–119, 2000.

Impact of Pneumococcal Conjugate Vaccination on Otitis Media: A Systematic Review

Reduced rates of consultations for otitis media after introduction of pneumococcal conjugate vaccines (PCVs) have been overinterpreted. This systematic review suggests that PCV is only somewhat modestly effective against all-cause otitis media.

Perceiving vowels from uniform spectra: Phonetic exploration of an auditory aftereffect

A carefully spoken vowel can generally be identified from the pattern of peaks and valleys in the envelope of its short-term power spectrum, and such patterning is usually necessary for the identification of the vowel. The present experiments demonstrate that segments of sound with uniform spectra, devoid of peaks and valleys, can be identified reliably as vowels under certain circumstances. In Experiment 1, 1,000 msec of a segment whose spectrum contained peaks in place of valleys and vice versa (i.e., the complement of a vowel) preceded a 25-msec spectral amplitude transition, during which the valleys became filled, leading into a 250-msec segment with a uniform spectrum. The segment with the uniform spectrum was identified as the vowel whose complement had preceded it. Experiment 2 showed that this effect was eliminated if the duration of the complement was less than 150 msec, if more than 500 msec of silence separated the uniform spectrum from the complement, or if the uniform spectrum and the complement were presented to different ears. This third result and comparisons with parameters of auditory aftereffects obtained by others with nonspeech stimuli suggest that the effect is rooted in peripheral adaptation processes and that central processes responsible for selective attention and perceptual grouping play only a minor role at most. Experiment 3 demonstrated that valleys in the spectral structure of a complement need be only 2 dB deep to generate the effect. The effect should therefore serve to enhance changes in spectral structure in natural speech and to alleviate the consequences of uneven frequency responses in communication channels.

The Four Alternative Auditory Feature test (FAAF)—linguistic and psychometric properties of the material with normative data in noise

The linguistic properties of the FAAF test material are expounded in relation to its objectives. It is shown from reference data that there are lexical effects inherent in the use of real-word minimal pairs rather than nonsense syllables. These are word-frequency effects upon phonemes in initial position and effects of imageability upon phonemes in final position. However, those effects are not large enough to undermine the use of the FAAF as an acoustical phonetically structured material reflecting the analysis of auditory information. Normative data on a range of signal-to-noise ratios are presented. These data have helped to delimit the subsets of items that best reflect variations in performance under easy and under difficult conditions. This offers a mapping of the percentage correct from scores at one or two fixed S/N ratios required for a given level of performance and hence permits comparison with SRT(N) measures.

Behaviour and cognitive outcomes from middle ear disease.

OBJECTIVES To resolve controversies over associations between a history of middle ear disease and psychosocial or cognitive/educational outcomes DESIGN Multipurpose longitudinal birth cohort study. Original cohort comprised all UK births between 5 and 11 April 1970; data were available for approximately 12 000 children at 5 years old and 9000 children at 10 years old. METHODS For 5 year old children, parent reported data were available on health, social, and behavioural factors, including data on two validated markers of middle ear disease. Cognitive tests were administered at 5 and 10 years of age, and behavioural problems rated at 10 years by the child’s teacher. RESULTS After adjustment for social background and maternal malaise, the developmental sequelae of middle ear disease remained significant even at 10 years. The largest effects were observed in behaviour problems and language test data at age 5, but effect sizes were modest overall. IMPLICATIONS These results provide an epidemiological basis for policies that aim to minimise the sequelae of middle ear disease by awareness in parents and preschool teachers, early referral, and intervention for more serious or persistent cases.

Can meaningful effective connectivities be obtained between auditory cortical regions

Structural equation modeling (SEM) of neuroimaging data can be evaluated both for the goodness of fit of the model and for the strength of path coefficients (as an index of effective connectivity). SEM of auditory fMRI data is made difficult by the necessary sparse temporal sampling of the time series (to avoid contamination of auditory activation by the response to scanner noise) and by the paucity of well-defined anatomical information to constrain the functional model. We used SEM (i.e., a model incorporating latent variables) to investigate how well fMRI data in four adjacent cortical fields can be described as an auditory network. Seven of the 14 models (2 hemispheres x (6 subjects and 1 group)) produced a plausible description of the measured data. Since the auditory model to be tested is not fully validated by anatomical data, our approach requires that goodness of fit be confirmed to ensure generalizability of connectivity patterns. For good-fitting models, connectivity patterns varied significantly across subjects and were not replicable across stimulus conditions. SEM of central auditory function therefore appears to be highly sensitive to the voxel-selection procedure and/or the sampling of the time series.

Topical intranasal corticosteroids in 4-11 year old children with persistent bilateral otitis media with effusion in primary care: double blind randomised placebo controlled trial

Objective To determine the clinical effectiveness of topical intranasal corticosteroids in children with bilateral otitis media with effusion. Design Double blind randomised placebo controlled trial. Setting 76 Medical Research Council General Practice Research Framework practices throughout the United Kingdom, between 2004 and 2007. Participants 217 children aged 4-11 years who had at least one practice recorded episode of otitis media or a related ear problem in the previous 12 months, and with bilateral otitis media with effusion confirmed by a research nurse using otoscopy plus micro-tympanometry (B/B or B/C2, modified Jerger types). Intervention Mometasone furoate 50 µg or placebo spray given once daily into each nostril for three months. Main outcome measures Proportions of children cured of bilateral otitis media with effusion assessed with tympanometry (C1 or A type) at one month (primary end point), three months, and nine months; adverse events; three month diary symptoms. Results 41% (39/96) of the topical steroid group and 45% (44/98) of the placebo group were cured in one or both ears at one month (difference favouring placebo 4.3% (95% confidence interval −9.3% to 18.1%). Poisson regression was done with adjustment for four pre-specified covariates (clinical severity, P=0.003; atopy, P=0.67; age, P=0.92; season, P=0.71). The adjusted relative risk at one month was 0.97 (95% confidence interval 0.74 to 1.26). At three months, 58% of the topical steroid group and 52% of the placebo group were cured (relative risk 1.23, 0.84 to 1.80). Diary symptoms did not differ between the two groups, and no significant harms were reported. Conclusions Topical steroids are unlikely to be an effective treatment for otitis media with effusion in general practice. High rates of natural resolution occurred by 1-3 months. Trial registration Current Controlled Trials ISRCTN38988331; National Research Register NO575123823; MREC 03/11/073.