Subject: A question about the confidence interval of objective audio quality (e.g. PEAQ), thans very much. From: Junyong You <junyong.you@xxxxxxxx> Date: Mon, 27 Oct 2008 12:17:07 +0200 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>This is a multi-part message in MIME format. ------=_NextPart_000_0075_01C9382D.EE2648E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi All, =20 I have a question about the confidence interval (CI) of the objective = audio quality. Of course, CI should be a concept with the subjective = quality scores. However, once we compute the objective score using one = audio quality metric (such as PEAQ, PESQ, NMR, whatever), how much is = this objective score believable with respect to the real quality, = supposing we don't know the real quality. For example, if the objective = PEAQ score is -1.5, can we believe the magnitude of the real quality is = [-2~-1]? =20 I tried to compute the CI by using the standard samples for PEAQ as = following: the objective quality (ODG) is computed for each sample = firstly, and then the difference (D) between ODG and subjective quality = (SDG) is gotten, for all samples. I assume the difference D is = approximately normally distributed, so the CI (e.g. 95%) of D can be = computed according to the T-distribution table, standard deviation of D, = and sample amount. For example, for PEAQ, the computed 95% CI is 0.16. = Then, if the ODG of one sequence is computed by using PEAQ, can we think = the subjective quality SDG should belong to the interval [ODG-0.16, = ODG+0.16] with the probability 95%? Is this way to compute the CI of = objective quality right? =20 I really appreciate any comment about this question, thank you so much. =20 Best regards, =20 Junyong You ------=_NextPart_000_0075_01C9382D.EE2648E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML xmlns=3D"http://www.w3.org/TR/REC-html40" xmlns:v =3D=20 "urn:schemas-microsoft-com:vml" xmlns:o =3D=20 "urn:schemas-microsoft-com:office:office" xmlns:w =3D=20 "urn:schemas-microsoft-com:office:word" xmlns:m =3D=20 "http://schemas.microsoft.com/office/2004/12/omml"><HEAD> <META http-equiv=3DContent-Type content=3D"text/html; = charset=3Diso-8859-1"> <META content=3D"MSHTML 6.00.6000.16735" name=3DGENERATOR> <STYLE>@xxxxxxxx { font-family: Cambria Math; } @xxxxxxxx { font-family: Calibri; } @xxxxxxxx Section1 {size: 8.5in 11.0in; margin: 1.0in 1.0in 1.0in 1.0in; } P.MsoNormal { FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: = "Calibri","sans-serif" } LI.MsoNormal { FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: = "Calibri","sans-serif" } DIV.MsoNormal { FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: = "Calibri","sans-serif" } A:link { COLOR: blue; TEXT-DECORATION: underline; mso-style-priority: 99 } SPAN.MsoHyperlink { COLOR: blue; TEXT-DECORATION: underline; mso-style-priority: 99 } A:visited { COLOR: purple; TEXT-DECORATION: underline; mso-style-priority: 99 } SPAN.MsoHyperlinkFollowed { COLOR: purple; TEXT-DECORATION: underline; mso-style-priority: 99 } SPAN.EmailStyle17 { COLOR: windowtext; FONT-FAMILY: "Calibri","sans-serif"; mso-style-type: = personal-compose } .MsoChpDefault { mso-style-type: export-only } DIV.Section1 { page: Section1 } </STYLE> <!--[if gte mso 9]><xml> <o:shapedefaults v:ext=3D"edit" spidmax=3D"1026" /> </xml><![endif]--><!--[if gte mso 9]><xml> <o:shapelayout v:ext=3D"edit"> <o:idmap v:ext=3D"edit" data=3D"1" /> </o:shapelayout></xml><![endif]--></HEAD> <BODY lang=3DEN-US vLink=3Dpurple link=3Dblue bgColor=3D#ffffff> <DIV> <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; LINE-HEIGHT: = normal"><SPAN=20 lang=3DEN-US=20 style=3D"FONT-SIZE: 12pt; mso-ascii-font-family: Calibri; = mso-fareast-font-family: 'Times New Roman'; mso-hansi-font-family: = Calibri; mso-bidi-font-family: 'Times New Roman'; mso-ansi-language: = EN-US">Hi=20 All,</SPAN><SPAN lang=3DEN-US=20 style=3D"FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman','serif'; = mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: = EN-US"><o:p></o:p></SPAN></P> <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; LINE-HEIGHT: = normal"><SPAN=20 lang=3DEN-US=20 style=3D"FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman','serif'; = mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: = EN-US"> <o:p></o:p></SPAN></P> <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; LINE-HEIGHT: = normal"><SPAN=20 lang=3DEN-US=20 style=3D"FONT-SIZE: 12pt; mso-ascii-font-family: Calibri; = mso-fareast-font-family: 'Times New Roman'; mso-hansi-font-family: = Calibri; mso-bidi-font-family: 'Times New Roman'; mso-ansi-language: = EN-US">I=20 have a question about the confidence interval (CI) of the objective = audio=20 quality. Of course, CI should be a concept with the subjective quality = scores.=20 However, once we compute the objective score using one audio quality = metric=20 (such as PEAQ, PESQ, NMR, whatever), how much is this objective score = believable=20 with respect to the real quality, supposing we don=92t know the real = quality. For=20 example, if the objective PEAQ score is -1.5, can we believe the = magnitude of=20 the real quality is [-2~-1]?</SPAN><SPAN lang=3DEN-US=20 style=3D"FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman','serif'; = mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: = EN-US"><o:p></o:p></SPAN></P> <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; LINE-HEIGHT: = normal"><SPAN=20 lang=3DEN-US=20 style=3D"FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman','serif'; = mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: = EN-US"> <o:p></o:p></SPAN></P> <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; LINE-HEIGHT: = normal"><SPAN=20 lang=3DEN-US=20 style=3D"FONT-SIZE: 12pt; mso-ascii-font-family: Calibri; = mso-fareast-font-family: 'Times New Roman'; mso-hansi-font-family: = Calibri; mso-bidi-font-family: 'Times New Roman'; mso-ansi-language: = EN-US">I=20 tried to compute the CI by using the standard samples for PEAQ as = following: the=20 objective quality (ODG) is computed for each sample firstly, and then = the=20 difference (D) between ODG and subjective quality (SDG) is gotten, for = all=20 samples. I assume the difference D is approximately normally = distributed, so the=20 CI (e.g. 95%) of D can be computed according to the T-distribution = table,=20 standard deviation of D, and sample amount. For example, for PEAQ, the = computed=20 95% CI is 0.16. Then, if the ODG of one sequence is computed by using = PEAQ, can=20 we think the subjective quality SDG should belong to the interval = [ODG-0.16,=20 ODG+0.16] with the probability 95%? Is this way to compute the CI of = objective=20 quality right?</SPAN><SPAN lang=3DEN-US=20 style=3D"FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman','serif'; = mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: = EN-US"><o:p></o:p></SPAN></P> <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; LINE-HEIGHT: = normal"><SPAN=20 lang=3DEN-US=20 style=3D"FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman','serif'; = mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: = EN-US"> <o:p></o:p></SPAN></P> <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; LINE-HEIGHT: = normal"><SPAN=20 lang=3DEN-US=20 style=3D"FONT-SIZE: 12pt; mso-ascii-font-family: Calibri; = mso-fareast-font-family: 'Times New Roman'; mso-hansi-font-family: = Calibri; mso-bidi-font-family: 'Times New Roman'; mso-ansi-language: = EN-US">I=20 really appreciate any comment about this question, thank you so=20 much.<o:p></o:p></SPAN></P> <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; LINE-HEIGHT: = normal"><SPAN=20 lang=3DEN-US=20 style=3D"FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman','serif'; = mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: = EN-US"><o:p> </o:p></SPAN></P> <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; LINE-HEIGHT: = normal"><SPAN=20 style=3D"FONT-SIZE: 12pt; mso-ascii-font-family: Calibri; = mso-fareast-font-family: 'Times New Roman'; mso-hansi-font-family: = Calibri; mso-bidi-font-family: 'Times New Roman'">Best=20 regards,</SPAN><SPAN=20 style=3D"FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman','serif'; = mso-fareast-font-family: 'Times New Roman'"><o:p></o:p></SPAN></P> <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; LINE-HEIGHT: = normal"><SPAN=20 style=3D"FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman','serif'; = mso-fareast-font-family: 'Times New Roman'"> <o:p></o:p></SPAN></P> <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; LINE-HEIGHT: = normal"><SPAN=20 style=3D"FONT-SIZE: 12pt; mso-ascii-font-family: Calibri; = mso-fareast-font-family: 'Times New Roman'; mso-hansi-font-family: = Calibri; mso-bidi-font-family: 'Times New Roman'">Junyong=20 You</SPAN></P></DIV></BODY></HTML> ------=_NextPart_000_0075_01C9382D.EE2648E0--