Experiments and modeling of perceived speech quality of long samples

Speech quality in cellular networks may vary significantly over time. Accessing the perceived speech quality aggregated over time, such as for an entire conversation, is desired to ensure customer satisfaction. Calculating average quality using common objective methods, which normally determine quality for short speech samples, has drawbacks. Subjective listening tests with long speech segments show that the perceived quality differs from the average quality calculated from a series of objective measurements. The overall perceived quality is affected by the brain\´s "ability" to forget and, hence, the last 30 to 40 s of speech form the basis for the subjective quality