Warbled tones, also known as frequency-modulated (FM) tones, are a second type ofstimulus that could be used in sound field to measure auditory thresholds in children. Afrequency-modulated tone means the signal being presented has a varied frequency. Thisstimulus is more focused at a specific frequency compared to narrowband noise. When used, theresults of the test are more frequency-specific than with the use of NBN (Shaw & Nikolopoulos,2004). Warbled tones might be more frequency-specific than NBN but they could also createmore standing waves within the sound booth. Overall, the use of warbled tones has beencomparable to the use of narrowband noise with similar minimum response levels (MRLs) and isan option for sound field testing (McDermott & Hodgson, 1982).