Background: Smartphone-based threshold audiometry with automated testing has the potential to provide affordable access to audiometry in underserved contexts. Purpose: To validate the threshold version (hearTest) of the validated hearScreen™ smartphone-based application using inexpensive smartphones (Android operating system) and calibrated supra-aural headphones. Research Design: A repeated measures within-participant study design was employed to compare airconduction thresholds (0.5-8 kHz) obtained through automated smartphone audiometry to thresholds obtained through conventional audiometry. Study Sample: A total of 95 participants were included in the study. Of these, 30 were adults, who had known bilateral hearing losses of varying degrees (mean age = 59 yr, standard deviation [SD] = 21.8; 56.7% female), and 65 were adolescents (mean age=16.5 yr, SD=1.2; 70.8% female), of which 61 had normal hearing and the remaining 4 had mild hearing losses. Data Analysis: Threshold comparisons were made between the two test procedures. The Wilcoxon signed-ranked test was used for comparison of threshold correspondence between manual and smartphone thresholds and the paired samples t test was used to compare test time. Results: Within the adult sample, 94.4% of thresholds obtained through smartphone and conventional audiometry corresponded within 10 dB or less. There was no significant difference between smartphone (6.75-min average, SD = 1.5) and conventional audiometry test duration (6.65-min average, SD = 2.5). Within the adolescent sample, 84.7% of thresholds obtained at 0.5, 2, and 4 kHz with hearTest and conventional audiometry corresponded within ≤5 dB. At 1 kHz, 79.3% of the thresholds differed by ≤10 dB. There was a significant difference (p<0.01) between smartphone (7.09 min, SD=1.2) and conventional audiometry test duration (3.23 min, SD = 0.6). Conclusions: The hearTest application with calibrated supra-aural headphones provides a cost-effective option to determine valid air-conduction hearing thresholds.