Spectral Ripple Discrimination in Normal-Hearing Infants.
David L Horn, Jong Ho Won, Jay T Rubinstein and 1 others
PMID 27768611WHAT IT FOUND
Normal-hearing 7-month-olds heard ripple patterns less finely than adults, especially when single-frequency cues were removed.
Their difficulty judging peak and trough intensity across frequencies means infant ripple scores should not be read as adult-like hearing.
Key findings
01Infants had poorer ripple discrimination than adults at 10 dB and 13 dB ripple depth, but not at 20 dB when ripple phase was constant.
02When ripple phase was randomized at 20 dB, infant mean ripple discrimination was poorer than adult mean performance.
03In the randomized-phase experiment, older listeners had higher ripple thresholds than younger listeners, but the slope of performance across ripple depths did not differ by age.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study tested normal-hearing infants, not infants using hearing aids or cochlear implants, so it does not show how device benefit should be measured. Fifty-eight 7-month-old infants and 36 young adults were initially recruited for Experiment 1, but 23 infants and 3 adults were excluded, leaving 35 infants and 33 adults analysed. Some infant thresholds were excluded because infants failed to reach criterion or completed too few trials, so the threshold sample was smaller than the completed sample. The task required many trials and multiple visits, which may not be practical in all clinical settings. Randomized ripple phase reduced within-channel cues, but the authors state that within-channel and temporal cues are not completely eliminated. The study measured ripple discrimination only, not speech perception in these infants, so it does not show that these thresholds predict speech understanding.
Declared interests
The authors reported no relevant financial disclosures or conflicts of interest. The article is listed as supported by NIH and non-U.S. government funding.
The easy way to misread this
Do not read infant ripple scores as evidence that a hearing aid or cochlear implant is working. The study tested normal-hearing infants and adults, not infants using devices, and it did not show that ripple thresholds predict speech understanding.