From mboxrd@z Thu Jan 1 00:00:00 1970 From: Raymond Yau Subject: Re: wrong decibel data? Date: Sat, 10 Apr 2010 12:25:42 +0800 Message-ID: References: <4BBF5F81.1010205@yellowcouch.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pw0-f51.google.com (mail-pw0-f51.google.com [209.85.160.51]) by alsa0.perex.cz (Postfix) with ESMTP id 339411037F3 for ; Sat, 10 Apr 2010 06:25:44 +0200 (CEST) Received: by pwj8 with SMTP id 8so2280715pwj.38 for ; Fri, 09 Apr 2010 21:25:43 -0700 (PDT) In-Reply-To: <4BBF5F81.1010205@yellowcouch.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: ALSA Development Mailing List List-Id: alsa-devel@alsa-project.org 2010/4/10 Werner Van Belle > Raymond Yau wrote: > > The dynamic range of 16bit audio is 96dB > > http://en.wikipedia.org/wiki/Dynamic_range > > > Yes about that. I always wondered how they come up with 96dB ? > > A perceived doubling of volume is normally assumed to be +3dB, > (log_10(2)=0.3) which means that if you have 16 bit audio you have 16 > 'doublings', or in essence only 48 dB. Even worse, since the last bit is > a sign bit, you essentially can only achieve a dynamic range of 45dB ! > > Now, I know this is off topic, but I never heard any good explanation > why CD audio is suddenly 45 dB ? If anybody knows, please share your > thoughts ! > > Wkr, > > Even when you are using floating point number Floating point numbers provide a way to trade off signal-to-noise ratio for an increase in dynamic range. For n bit floating-point numbers, with n-m bits in the mantissa and m bits in the exponent DR is still a finite number http://en.wikipedia.org/wiki/Signal-to-noise_ratio