Figure 1: Pure tone audiogram recorded at the initial visit (dotted line) and a 1 week later (line). Hearing deteriorates bilaterally in a week in spite of the steroid treatment. Each symbol indicates as follows: circle; right ear air-conduction, cross; left ear airconduction, downward arrow; no response at the maximum output of the audiometer.B) Distortion products (DP) of otoacoustic emission a week later the initial presentation. The DP response curve above the noise level in lower frequencies below 2 kHz is regarded as positive bilaterally. (DP type; 2f1-f2 evoked by two tons of frequencies f1<f2. Stimulus intensity levels of primary tones; L1=65dB SPL, L2=55dB SPL)