The rise and fall of fasciculations in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis is a devastating neurodegenerative disease with a median survival of 3 years from symptom onset. Accessible and reliable biomarkers of motor neuron decline are urgently needed to quicken the pace of drug discovery. Fasciculations represent an early pathophysiological hallmark of amyotrophic lateral sclerosis and can be reliably detected by high-density surface electromyography.

Arrays of rectangular subcritical speech bands: Intelligibility improved by noise-vocoding and expanding to critical bandwidths.

A previous study [Warren, Bashford, and Lenz (2017). J. Acoust.

Maintaining intelligibility at high intensities with arrays of subcritical width speech bands and interpolated noise.

Speech intelligibility normally declines at high intensities, but this "rollover" effect decreases when steep filtering reduces sentences to an array of rectangular subcritical bands. The present study found that interpolating low intensity noise between the speech bands further decreases rollover, supporting the hypothesis that rollover is normally reduced by lateral inhibition of input from rate-saturated auditory nerve fibers. With noise also present within the speech (a 15 dB signal-to-noise ratio) an array of 6%-wide speech bands with interpolated noise was found to be 9% more intelligible at 100 dB than a spectrally continuous band of speech covering the same frequency range.

Critical bandwidth speech: Arrays of subcritical band speech maintain near-ceiling intelligibility at high amplitudes.

Removal of transition bands from narrow speech passbands through very steep filtering has made it possible to isolate and determine (for the first time) intelligibility of critical bandwidth as well as subcritical bandwidth speech. These rectangular bands have unique intelligibilities when heard singly, paired, or in various multiband arrays spanning the speech spectrum. Thus, a particular sparse spectral array of unfamiliar everyday sentences in this study has demonstrated 98% intelligibility up to 100 dB.

Remarkable motor recovery after riboflavin therapy in adult-onset Brown-Vialetto-Van Laere syndrome.

The clinical diagnosis of Brown-Vialetto-Van Laere syndrome in this woman with rapidly progressive pontobulbar palsy led to empirical high-dose oral riboflavin (1200 mg/day) therapy. This resulted in a dramatic improvement in her motor function from being anarthric, dysphagic, tetraparetic and in ventilatory failure to living independently with mild dysarthria and distal limb weakness. DNA sequencing of the SLC52A3 gene found compound heterozygous C-terminus mutations, V413A1/D461Y, consistent with recent reports of mutations within the riboflavin transporter genes (SLC52A2 and SLC52A3) in this condition.

How broadband speech may avoid neural firing rate saturation at high intensities and maintain intelligibility.

Three experiments examined the intelligibility enhancement produced when noise bands flank high intensity rectangular band speech. When white noise flankers were added to the speech individually at a low spectrum level (-30 dB relative to the speech) only the higher frequency flanker produced a significant intelligibility increase (i.e.

When intelligibilities of paired speech bands do not behave the way they are supposed to.

Two rectangular 1/3-octave passbands were derived from different spectral regions of everyday sentences, with the intelligibility of one band approximately twice the others. Both passbands were then filtered to produce a series of narrower rectangular passbands. Each of the original 1/3-octave passbands in turn served as the fixed bandwidth "pedestal" and was paired with each of the series of narrower passbands of the other band.

Maintaining intelligibility at high speech intensities: evidence of lateral inhibition in the lower auditory pathway.

Three experiments examined the intelligibility enhancement produced when noise bands flank high intensity narrowband speech. Enhancement was unaffected by noise gating (experiment 1), ruling out peripheral adaptation as a source, and was also unaffected by interaural decorrelation of noise bands flanking diotic speech (experiment 2), indicating that enhancement occurs prior to binaural processing. These results support previous suggestions that intelligibility loss at high intensities is reduced by lateral inhibition in the cochlear nuclei.

Enhancing the intelligibility of high intensity speech: Evidence of inhibition in the lower auditory pathway.

Intelligibility of narrowband speech declines considerably at high intensities, but substantial recovery from this "rollover" occurs when flanking noise bands are added. The present study employed two types of added noise: narrowband noise matching the spectral limits of the rectangular speech band (producing within band masking) versus broadband noise (producing within band masking plus simultaneous enhancement by out of band noise components). When noise added to diotic speech in experiment 1 was interaurally uncorrelated rather than diotic, intelligibility increased 5%, regardless of noise bandwidth.

An alternative to the computational Speech Intelligibility Index estimates: direct measurement of rectangular passband intelligibilities.

The need for determining the relative intelligibility of passbands spanning the speech spectrum has been addressed by publications of the American National Standards Institute (ANSI). When the Articulation Index (AI) standard (ANSI, S3.5, 1969, R1986) was developed, available filters confounded passband and slope contributions.

When noise vocoding can improve the intelligibility of sub-critical band speech.

This study examined the redundancy of spectral and temporal information in everyday sentences, which were reduced to 16 rectangular spectral bands having center frequencies ranging from 250 to 8000 Hz, spaced at 1/3 octave intervals. High-order filtering eliminated contributions from transition bands, and the widths of the resulting effectively rectangular speech bands were varied from 4% down to 0.5%.

The spread and density of the phonological neighborhood can strongly influence the verbal transformation illusion.

When a recorded verbal stimulus repeats over and over, adaptation occurs and listeners hear competing forms. Reports of these "verbal transformations" (VTs) were obtained for 36 consonant-vowel (CV) syllables that varied both in frequency-weighted neighborhood density (ranging from 12.73 to 90.

Is intelligibility of adjacent passbands hypoadditive or hyperadditive?

Based on their own findings and reports from other laboratories, H. Müsch and S. Buus [H.

Evoking biphone neighborhoods with verbal transformations: illusory changes demonstrate both lexical competition and inhibition.

When a recorded verbal stimulus repeats over and over, perceptual changes occur and listeners hear competing forms. These verbal transformations (VTs) were obtained for a phonemically related set of 24 consonant-vowel syllables that varied widely in frequency-weighted neighborhood density (FWND). Listener's initial transformations involving substitution of consonants versus vowels were strongly correlated with the lexical substitution neighborhood [r=+0.

Polling the effective neighborhoods of spoken words with the verbal transformation effect.

Studies of the effects of lexical neighbors upon the recognition of spoken words have generally assumed that the most salient competitors differ by a single phoneme. The present study employs a procedure that induces the listeners to perceive and call out the salient competitors. By presenting a recording of a monosyllable repeated over and over, perceptual adaptation is produced, and perception of the stimulus is replaced by perception of a competitor.

Intelligibilities of 1-octave rectangular bands spanning the speech spectrum when heard separately and paired.

There is a need, both for speech theory and for many practical applications, to know the intelligibilities of individual passbands that span the speech spectrum when they are heard singly and in combination. While indirect procedures have been employed for estimating passband intelligibilities (e.g.

Enhancing intelligibility of narrowband speech with out-of-band noise: evidence for lateral suppression at high-normal intensity.

Previous studies have shown that the intelligibility of filtered speech can be enhanced by filling stopbands with noise. The present study found that this enhancement occurred only when speech intensity was sufficiently high to degrade performance. Intelligibility decreased by about 15% when narrowband speech was increased from 45 to 65 dBA (corresponding to broadband speech levels of about 60 and 80 dBA), and decreased by 20% at a level of 75 dBA.

Intelligibility of bandpass filtered speech: steepness of slopes required to eliminate transition band contributions.

Despite the recognition that the steepness of filter slopes can play an important role in the intelligibility of bandpass speech, there has been no systematic examination of its importance. The present study used high orders of finite impulse response (FIR) filtering to produce slopes ranging from 150 to 10,000 dB/octave. The slopes flanked 1/3-octave passbands of everyday sentences having a center frequency of 1500 Hz (the region of highest intelligibility for the male speaker's voice).

Relative contributions of passband and filter skirts to the intelligibility of bandpass speech: Some effects of context and amplitude.

Warren et al. (1995) reported over 90% intelligibility for everyday sentences reduced to a 1/3-octave band (center frequency 1,500 Hz, slopes 100 dB/octave, slow-rms peak levels 75 dB). To investigate the basis of this high intelligibility, Warren and Bashford (1999) partitioned the sentences.