Baseline and Endpoint auditory tests (ABR and DPOAE): Macrophage ablation followed by partial repopulation protected against cisplatin-induced hearing loss and OHC dysfunction (Experiment 1) (Manuscript: Fig. 2; Fig. S2-1, Fig. S2-2_Supp Fig 5-3)

Prior to the start of PLX3397 chow pre-treatment and at the end of the cisplatin administration protocol, mice underwent two types of auditory tests: auditory brainstem responses (ABRs; measure hearing sensitivity) and distortion product otoacoustic emissions (DPOAEs; indirectly measure outer hair cell function). These data suggest that partial macrophage ablation protected against cisplatin-induced hearing loss and OHC dysfunction (Experiment 1).For ABR measurements, subcutaneous needle electrodes (Rhythmlink, Columbia, SC, USA) were placed behind left pinna of the test ear (reference), vertex (active), and near the tail of the mouse (ground). Tone-burst stimuli (Cos2, 3 msec, 0.5 msec rise/fall in alternating polarity) were presented at a rate of 29.9/sec at 8, 11.2, 16, 22.4, 32, and 40 kHz starting at 90dB SPL. At each sound level, 1024 waveforms were averaged, amplified (20x), and filtered (HP: 300Hz, LP: 3kHz, NT: 60Hz). At near-threshold sound pressure levels (SPL), the ABR waveforms were recorded twice, and two waveforms were superimposed for comparison. ABR threshold was defined as the lowest stimulus intensity that resulted in a reproducible waveform displaying identifiable peaks.DPOAEs were measured in response to two primary pure tones, f1 and f2, generated by Multi Field 1 speakers. Two primary tones were presented at 6 frequency pairs, where f2 corresponded to ABR test frequencies (f2 = 8, 11.2, 16, 22.4, 32, 40kHz; f2/f1 = 1.25). The sound level was increased in 5dB steps from 30dB to 90dB. At each sound level, 512 responses were averaged. DPOAE at 2f1-f2 was recorded in the mouse inner ear canal using an ER-10B+ microphone (Etymotic, Elk Grove Village, IL, USA) connected to a modified pipette tip to fit the mouse external ear canal. Biological noise floors and amplitudes were calculated for each treatment group and plotted relative to each other.