user18284: I have video tutorials that I am producing using Camtasia using the following process:

Write Script.
Record a voice over.
Record screen while listening the voice over steps.
merge sound and screen recording.

My recordings are little a bit slow and boring and I would like to speed them up like YouTube speed 1.25X, but whenever I speed them up my voice tone changes badly (get more thinner) unlike YouTube Playback, the voice flows at higher rate and voice tone is normal.
How Can I speed them up without affecting my voice tone?

user12153: You don't do this in Camtasia as it doesn't appear that Camtasia supports pitch shifting at this point although there has definitely been some discussion of the topic for quite some time. 
There are alternate solutions however, ffmpeg has this capability through the atempo and aserate audio filters, I understand that you can do this with audacity and sox as well. If you have any interest in any of these approaches and would like further detail drop me a comment and I'll do my best to accommodate you.
According to @Mulvya you can also accomplish this with an ffmpeg build compiled to support librubberband You can compile it your self or there are Windows XP compatible builds available here which I've confirmed run under Wine
There's also a stand alone utility that I haven't used that you can obtain from the librubberband link above. It appears that that is limited to adjusting WAV files.
Some sources:
https://superuser.com/questions/292833/how-to-change-audio-frequency
https://superuser.com/questions/1118826/change-tone-pitch-for-file-audio
https://www.ffmpeg.org/documentation.html
https://feedback.techsmith.com/techsmith/topics/speeding_up_the_video_speed_without_effecting_audio_pitch

18284: <p>I have video tutorials that I am producing using Camtasia using the following process:</p>

<ol>
<li>Write Script.</li>
<li>Record a voice over.</li>
<li>Record screen while listening the voice over steps.</li>
<li>merge sound and screen recording.</li>
</ol>

<p>My recordings are little a bit slow and boring and I would like to speed them up like YouTube speed 1.25X, but whenever I speed them up my voice tone changes badly (get more thinner) unlike YouTube Playback, the voice flows at higher rate and voice tone is normal.</p>

<p>How Can I speed them up without affecting my voice tone?</p>
 12153: <p>You don't do this in Camtasia as it doesn't appear that Camtasia supports pitch shifting at this point although there has definitely been some <a href="https://feedback.techsmith.com/techsmith/topics/speeding_up_the_video_speed_without_effecting_audio_pitch" rel="nofollow noreferrer">discussion of the topic</a> for quite some time. </p>

<p>There are alternate solutions however, ffmpeg has this capability through the <a href="https://www.ffmpeg.org/ffmpeg-filters.html#atempo" rel="nofollow noreferrer">atempo</a> and <a href="https://www.ffmpeg.org/ffmpeg-filters.html#asetrate" rel="nofollow noreferrer">aserate</a> audio filters, I understand that you can do this with audacity and sox as well. If you have any interest in any of these approaches and would like further detail drop me a comment and I'll do my best to accommodate you.</p>

<p>According to @Mulvya you can also accomplish this with an ffmpeg build compiled to support <a href="http://breakfastquay.com/rubberband/" rel="nofollow noreferrer">librubberband</a> You can compile it your self or there are Windows XP compatible builds available <a href="https://sourceforge.net/projects/ffmpegwindowsbi/" rel="nofollow noreferrer">here</a> which I've confirmed run under <a href="https://www.winehq.org/" rel="nofollow noreferrer">Wine</a></p>

<p>There's also a stand alone utility that I haven't used that you can obtain from the librubberband link above. It appears that that is limited to adjusting WAV files.</p>

<p>Some sources:</p>

<p><a href="https://superuser.com/questions/292833/how-to-change-audio-frequency">https://superuser.com/questions/292833/how-to-change-audio-frequency</a></p>

<p><a href="https://superuser.com/questions/1118826/change-tone-pitch-for-file-audio">https://superuser.com/questions/1118826/change-tone-pitch-for-file-audio</a></p>

<p><a href="https://www.ffmpeg.org/documentation.html" rel="nofollow noreferrer">https://www.ffmpeg.org/documentation.html</a></p>

<p><a href="https://feedback.techsmith.com/techsmith/topics/speeding_up_the_video_speed_without_effecting_audio_pitch" rel="nofollow noreferrer">https://feedback.techsmith.com/techsmith/topics/speeding_up_the_video_speed_without_effecting_audio_pitch</a></p>
