RE: Screen Readers | Rate = Words Per Minute

This is great Christophe. If I understand the formulas correctly – then the fastest rate (100%) for NVDA using eSpeak is 310 WPM (of course, that is you are not using the rate boost check box)?

Thanks!

Isaiah M. Wright
Usability Research  | Integrated Channels & Experience
440 S. Church St., Charlotte NC 28202
T + 704 444 4694  |  isaiah.wright@ally.com
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From: Christophe Strobbe [mailto:strobbe@hdm-stuttgart.de]
Sent: Thursday, May 11, 2017 11:55 AM
To: w3c-wai-ig@w3.org
Subject: Re: Screen Readers | Rate = Words Per Minute

Hi,

On 9/05/2017 16:51, Wright, Isaiah wrote:
(...)
I have access to NVDA but the rate is by percentage instead of words per minute. Is there a chart out there that translates rate percentage into words per minute?

If you really need conversion formulas, here is the best I found for NVDA:

(nvdaRate / 100) * (maxRate - minRate) + minRate = wpm (with with maxrate = 390 and minrate = 80)
This formula assumes eSpeak; it may not be a very good approximation for other TTS engines.

For Orca, I have used the following two formulas:
(1) wpm = eSpeakNormalRate + (eSpeakNormalRate - eSpeakMinRate) * (r-50) / 50
(2) wpm = eSpeakNormalRate + (eSpeakMaxRate - eSpeakNormalRate) * (r-50) / 50
where:
* r = Orca’s speech rate value
* eSpeakNormalRate = eSpeak’s normal speed on GNOME; here = 160
* eSpeakMinRate = eSpeak’s minimum speed on GNOME; here = 80
* eSpeakMaxRate = eSpeak’s maximum speed on GNOME; here = 310

The first formula is used for Orca speech rates lower than 50; the second is used when Orca's speech rate is 50 or higher.

Warning: I have not checked the accuracy of these formulas since April 2014.

Best regards,

Christophe Strobbe



Cheers,
Isaiah M. Wright
Usability Research  | Integrated Channels & Experience
440 S. Church St., Charlotte NC 28202
T + 704 444 4694  |  isaiah.wright@ally.com<mailto:isaiah.wright@ally.com>
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Christophe Strobbe

Akademischer Mitarbeiter

Responsive Media Experience Research Group (REMEX)

Hochschule der Medien

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Tel. +49 711 8923 2749



“I drink tea and I know things.”

Falsely attributed to Christophe Lannister.