Identifying cues for tone-in-noise detection using decision variable correlation in the budgerigar (Melopsittacus undulatus)

Abstract

Previous studies evaluated cues for masked tone detection using reproducible noise waveforms. Human results founded on this approach suggest that tone detection is based on combined energy and envelope (ENV) cues, but detection cues in nonhuman species are less clear. Decision variable correlation (DVC) was used to evaluate tone-in-noise detection cues in the budgerigar, an avian species with human-like behavioral sensitivity to many complex sounds. DVC quantifies a model's ability to predict trial-by-trial variance in behavioral responses. Budgerigars were behaviorally conditioned to detect 500-Hz tones in wideband (WB; 100-3000 Hz) and narrowband (NB; 452-552 Hz) noise. Behavioral responses were obtained using a single-interval, two-alternative discrimination task and two-down, one-up adaptive tracking procedures. Tone-detection thresholds in WB noise were higher than human thresholds, putatively due to broader peripheral frequency tuning, whereas NB thresholds were within $1 dB of human results. Budgerigar average hit and false-alarm rates across noise waveforms were consistent, highly correlated across subjects, and correlated to human results. Trial-by-trial behavioral results in NB noise were best explained by a model combining energy and ENV cues. In contrast, WB results were better predicted by ENV-based or multiple-channel energy detector models. These results suggest that budgerigars and humans use similar cues for tone-in-noise detection. V

Normal Tone-In-Noise Sensitivity in Trained Budgerigars despite Substantial Auditory-Nerve Injury: No Evidence of Hidden Hearing Loss

“…7, right). The magnitude of the DVC was generally slightly greater for tone-plus-noise trials than noise trials, as observed previously (Henry et al, 2020), and somewhat lower for lowlevel, higher-frequency stimuli (Fig. 8, top left).…”

“…In contrast, spontaneous activity is unimodally distributed in birds rather than bimodal as in mammals, and units without spontaneous activity are not observed. In light of these basic physiological similarities, as well as findings of human-like behavioral performance in normal-hearing budgerigars (Saunders et al, 1979;Henry et al, 2017bHenry et al, , 2020Dent et al, 2000;Dooling et al, 2000), it seems promising that behavioral results in AN-damaged budgerigars might be observed in humans or mammalian animal models for the same degree of neural loss.…”

“…DVCs quantify the ability of a model to predict trial-by-trial observer responses (Sebastian et al, 2017;Sebastian and Geisler, 2018), thereby providing greater potential insight into an individual's detection strategy than traditional analyses of detection thresholds alone. A previous study in normal-hearing budgerigars found that a decision variable combining single-channel energy and envelope cues could explain significantly greater variance in behavioral responses to 500-Hz TIN stimuli than models based on either cue alone (Henry et al, 2020), a result consistent with numerous human studies of TIN detection implicating envelope-related detection strategies (Kidd et al, 1989;Richards, 1992;Kohlrausch et al, 1997;Davidson et al, 2006Davidson et al, , 2009Mao et al, 2013. Here, the same DVC approach and model were used to evaluate TIN detection strategies in budgerigars with normal hearing and KA-induced AN damage for frequencies from 0.5 to 4 kHz.…”

“…Random variation in stimulus level across trials (i.e., roving level) decreases the reliability of single-channel energy cues for TIN detection (Kidd et al, 1989;Richards, 1992) and thus is expected to cause threshold elevation proportional to the degree by which the subject uses single-channel energy cues to perform the task (Henry et al, 2020;Leong et al, 2020). In control animals, threshold shifts observed during the roving-level part of the testing session were generally slightly above 0 dB and almost invariably ,2 dB (Fig.…”

“…The decision variable was calculated for each stimulus, shortened in duration to the animal's reaction time on that trial, as the weighted sum of single-channel energy and envelope cues. This relatively simple and physiologically grounded model explains greater variance in 500-Hz TIN responses in this species than alternative models based on either cue or incorporating temporal fine structure information (Henry et al, 2020). The energy cue, E, was calculated as the root-meansquare amplitude of the stimulus waveform in decibels.…”