Event Type: Audio

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Event Type: Audio

Event Type: Audio
Test Mode	Severity	Event	Description
Non-Referenced	Warning	Low Volume Alarm	See "Low Volume Alarm Event".
Non-Referenced	Warning	Clipping	See "Clipping Event"
Non-Referenced	Warning	High Volume Alarm	See "High Volume Alarm Event"
Non-Referenced	Warning	Dropput	See "Dropout Event"
Non-Referenced	Warning	Glitch	See "Glitch Event"
Referenced	Info	TestID Found	See "Test ID Found Event"
Referenced	Warning	Test Script Not Found	See "Test ID Found Event"
Referenced	Error	Invalid Test Script	See "Invalid Test Script Event"
Referenced	Error	Synchronization Lost	See "Synchronization Lost Event"
Referenced	Error	Unexpected Frequency	See "Unexpected Frequency Event"
Referenced	Error	Unexpected Level	See "Unexpected Level Event"
Referenced	Error	Unexpected Duration	See "Unexpected Duration Event"
Referenced	Error	Amplitude Fluctuations	See "Amplitude Fluctuation Event"
Referenced	Error	Unexpected Phase Change	See "Unexpected Phase Change Event"
Referenced	Error	Excess Noise	See "Excess Noise Event"
Referenced	Error	Clipping	See "Clipping Event"
Referenced	Error	CVSD HF Level Too High	See "CVSD HF Level Too High Event"
Referenced	Info	End of Test Event	See "End of Test Event"

Clipping

The number of consecutive samples needed to qualify as a clipping event depends on both sample rate and number of bits per sample. Table 1 specifies the number of consecutive samples at the maximum value level that will generate a Clipping event.

Clipping Event Thresholds
Consecutive Samples	Sample Rate, Samples/sec	Resolution, bits
3	8000	16
5	16000	16
11	41000	16
2	64000	16
12	48000	16
24	96000	16

Clipping Event Thresholds
Consecutive Samples	Sample Rate, Samples/sec	Resolution, bits
3	8000	16
5	16000	16
11	41000	16
2	64000	16
12	48000	16
24	96000	16

Dropout

Dropout events are reported when the average audio level (RMS) is initially above the Measurement Threshold, then falls below the Silence Threshold, and then quickly rises above the Measurement Threshold again ). This approach largely disqualifies the natural inter-syllable silence and pauses that occur in natural speech, but will detect gaps caused by dropped data. Note that the system does not report dropouts that begin at very low energy levels.

Audio Dropout description

Dropout: Measurement and Silence Threshold

Glitch

The Glitch event is reported whenever an extremely large sample to sample amplitude transition occurs that has little or no probability of occurring within natural speech or music. As illustration, back to back +N, -N, …, +N, -N values (where N is any non-zero number), represents energy at the Nyquist frequency, or ½ the sample rate. Neither speech nor music contain average energy levels at this frequency more the 20 dB below nominal. However, moderately large sample to sample changes in amplitude do occur, and these naturally limit how sensitive this measure can be configured.

The system uses back to back transition levels of 90 dB for music and 40 dB for speech as the threshold for reporting the Glitch event.

Such dramatic changes would typically happen only in the face of dropped samples, and serve as an additional means of detecting gross abnormalities

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