To attach a file as a comment
Click the File tool at Comment > Attachments for an attach file cursor 
.
Go to the page and place in your PDF document where you want to add a file attachment icon and click.
In the Open dialog box, browse for a file, then click Open.
In the File Attachment Properties dialog box, select display and other properties, then close it.
An attachment symbol appears in your document. Double-click this symbol to open the attachment.
Click Yes in the dialog box that appears, to confirm opening.
You can also attach files that are not comments or annotations. Do this in the Attachments panel.
To attach a WAV sound file as a comment
Click the Audio tool at Comment> Attachments for an attach sound cursor 
.
Go to the page and place in your PDF document where you want to add a sound file attachment icon and click.
In the Attach Sound dialog box and click Browse, then select a sound file and open it.
Click the 
Play button to check file contents, or
Click the 
Record button to make a sound file from your dictation if you have a suitable program and equipment.
In the Sound Attachment Properties dialog box, select display and other properties, then close it.
A sound symbol appears in your document. You can change the symbol icon in the Sound Attachment Properties dialog box. Double-click this symbol to access settings; to hear the attached sound right-click and choose Play.
Click Yes in the dialog box that appears, to confirm playing.
You can also attach a sound file that is not a comment. In this case a wide range of file types is supported, including mp3. Do this in the Attachments Panel.
Note
Files or Sounds attached as comments can be removed with the Flatten Document command. In this case attachments added through the Attachments Panel are not removed, because they are not comments or annotations. All attachments (comments or not) can be removed with the Remove Document Elements command.