Update speech-synthesis-markup-voice.md

Author: sally-baolian

articles/ai-services/speech-service/speech-synthesis-markup-voice.md

@@ -307,7 +307,7 @@ The following table describes the usage of the `prosody` element's attributes:
 
 | Attribute | Description | Required or optional |
 | ---------- | ---------- | ---------- |
-| `contour` | Contour represents changes in pitch. These changes are represented as an array of targets at specified time positions in the speech output. Sets of parameter pairs define each target. For example: <br/><br/>`<prosody contour="(0%,+20Hz) (10%,-2st) (40%,+10Hz)">`<br/><br/>The first value in each set of parameters specifies the location of the pitch change as a percentage of the duration of the text. The second value specifies the amount to raise or lower the pitch by using a relative value or an enumeration value for pitch (see `pitch`). | Optional |
+| `contour` | Contour represents changes in pitch. These changes are represented as an array of targets at specified time positions in the speech output. Sets of parameter pairs define each target. For example: <br/><br/>`<prosody contour="(0%,+20Hz) (10%,-2st) (40%,+10Hz)">`<br/><br/>The first value in each set of parameters specifies the location of the pitch change as a percentage of the duration of the text. The second value specifies the amount to raise or lower the pitch by using a relative value or an enumeration value for pitch (see `pitch`). Pitch contour doesn’t work on single words and short phrases. It is recommended to adjust the pitch contour on whole sentences or long phrases.| Optional |
 | `pitch`   | Indicates the baseline pitch for the text. Pitch changes can be applied at the sentence level. The pitch changes should be within 0.5 to 1.5 times the original audio. You can express the pitch as:<ul><li>An absolute value: Expressed as a number followed by "Hz" (Hertz). For example, `<prosody pitch="600Hz">some text</prosody>`.</li><li>A relative value:<ul><li>As a relative number: Expressed as a number preceded by "+" or "-" and followed by "Hz" or "st" that specifies an amount to change the pitch. For example: `<prosody pitch="+80Hz">some text</prosody>` or `<prosody pitch="-2st">some text</prosody>`. The "st" indicates the change unit is semitone, which is half of a tone (a half step) on the standard diatonic scale.<li>As a percentage: Expressed as a number preceded by "+" (optionally) or "-" and followed by "%", indicating the relative change. For example: `<prosody pitch="50%">some text</prosody>` or `<prosody pitch="-50%">some text</prosody>`.</li></ul></li><li>A constant value:<ul><li>`x-low` (equivalently 0.55,-45%)</li><li>`low` (equivalently 0.8, -20%)</li><li>`medium` (equivalently 1, default value)</li><li>`high` (equivalently 1.2, +20%)</li><li>`x-high` (equivalently 1.45, +45%)</li></ul></li></ul> | Optional |
 | `range`| A value that represents the range of pitch for the text. You can express `range` by using the same absolute values, relative values, or enumeration values used to describe `pitch`.| Optional |
 | `rate` | Indicates the speaking rate of the text. Speaking rate can be applied at the word or sentence level. The rate changes should be within `0.5` to `2` times the original audio. You can express `rate` as:<ul><li>A relative value: <ul><li>As a relative number: Expressed as a number that acts as a multiplier of the default. For example, a value of `1` results in no change in the original rate. A value of `0.5` results in a halving of the original rate. A value of `2` results in twice the original rate.</li><li>As a percentage: Expressed as a number preceded by "+" (optionally) or "-" and followed by "%", indicating the relative change. For example: `<prosody rate="50%">some text</prosody>` or `<prosody rate="-50%">some text</prosody>`.</li></ul><li>A constant value:<ul><li>`x-slow` (equivalently 0.5, -50%)</li><li>`slow` (equivalently 0.64, -46%)</li><li>`medium` (equivalently 1, default value)</li><li>`fast` (equivalently 1.55, +55%)</li><li>`x-fast` (equivalently 2, +100%)</li></ul></li></ul> | Optional |