You may want to record your own voice for a student to listen to as feedback for a submitted assignment in Blackboard. Here is how to use an MP3 Recorder website to make this easy.
UPDATE: The recordmp3.org service appears to be down. Try alternatives recordmp3online.com or vocaroo.com
The steps involved are:
1. Navigate to the student's attempt in the Grade Center of your course.
2. Use recordmp3.org or recordmp3online.com or vocaroo.com to record your commentary / feedback.
3. Add the audio file you recorded to the feedback section for the assignment attempt.
Here is a video showing the entire process:
(Alternative link to high-resolution video here)
Note: if you would like to include a screen-capture with your audio feedback, try this alternative method using Jing.