APRIL 4, 2003

Is music in compressed file format really of lower sound quality?

Thanks to the Canadian Private Copying Collective for allowing us to distribute our report on the sound quality of compressed music files. This report is available on our Web site. Here is the report summary.

This study is based on the results of a Web survey conducted in December 2002. The respondents were 258 Canadians age 12 to 49 who had a multimedia computer with Internet access in their homes at the time of the survey. Each respondent compared the sound quality of two versions of the same selections of music: the original version and a version that had been compressed using the MP3 algorithm. The following conclusions were drawn from the responses.

In 14% of the cases, the respondents correctly identified the original track of music as being of better quality.

• In 41% of the comparisons that they made, the respondents judged the two versions to be of similar quality.
• In 37% of the cases, the respondents identified the original track as having better sound quality, but from this value we must subtract the 22% of the respondents who preferred the sound quality of the compressed track.
• The equipment used did not affect the results in any statistically significant way.
• The sound quality of selections of modern and classical music was more readily discernible than that of selections of rock, jazz, and hardcore.

The respondents who did perceive a difference in the sound quality of the tracks they listed to assigned it a monetary value of 20%.

• On average, the respondents were prepared to pay $18.30 for an album with the better sound quality that they had discerned, or $3.63 more than for an album of perceived poorer sound quality.
• The assigned monetary value of the perceived difference in sound quality was the same regardless of whether the track in question was objectively the one of better quality or the one of worse quality. Thus this value depended entirely on perceived sound quality.
• The monetary value ascribed to the better sound quality was the same for all five genres of music tested, but greater for the genres that the particular respondent liked best.
• The assigned monetary value of the better sound quality decreases as the comparison price for the lower sound quality increases.

METHODOLOGY

This study is based on data gathered from 258 respondents in an on-line survey conducted from December 6 to 18, 2002. These respondents were recruited by Echo Sondage telephone, on December 3 and 4, from a list of the respondents to Circum Network Inc.'s Music Monitor survey who had reported that they had a multimedia computer and Internet access in their homes and had agreed to be contacted again. Only persons who were age 12 to 49 at the time they were originally interviewed and whose interviews were completed between January and September 2002 were included in this study.

In the recruitment phase of this study, the refusal rate and the response rate, as calculated by industry- standard methods, were 23% and 44%, respectively. In the data-collection phase, the response rate was 59%.

A random sample of the size used in this study produces a margin of sampling error no greater than ± 4.7 percentage points for proportion estimates for the entire sample, taking the effects associated with the sampling plan into account. The margins of sampling error for sub-groups within the sample are larger.

The estimates produced from these data were adjusted for gender, age, region of residence, and mother tongue, so as to match the distributions calculated in the Music Monitor survey for the population segment used in this study.

The survey questionnaire was designed to meet two research objectives. It comprised six sections, and the number of questions asked varied with the responses provided. The minimum was 6 questions, and the maximum was 23. A music CD prepared especially for this study was sent to each respondent's home. This CD contained five selections of five different genres of music, each recorded in two different formats. The respondents were asked to listen to both versions of each selection on their own audio equipment and to indicate whether either one had better sound quality than the other.

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