How about this one:

do shell script "afplay '/System/Library/Components/CoreAudio.component/Contents/SharedSupport/SystemSounds/dock/drag to trash.aif'"

Update:

To address your comment, this is covered in Technical Note TN2065 - do shell script in AppleScript under Other Concerns where it says:

"... how do I make do shell script not wait until the command completes?"

Use do shell script \"command &> file_path &\". do shell script will return immediately with no result and your AppleScript script will be running in parallel with your shell script. The shell script’s output will go into file_path; if you don’t care about the output, use /dev/null.

Example:

do shell script "afplay '/System/Library/Components/CoreAudio.component/Contents/SharedSupport/SystemSounds/dock/drag to trash.aif' > /dev/null &"

How about this one:

do shell script "afplay '/System/Library/Components/CoreAudio.component/Contents/SharedSupport/SystemSounds/dock/drag to trash.aif'"

Update:

To address your comment, this is covered in Technical Note TN2065 - do shell script in AppleScript under Other Concerns where it says:

"... how do I make do shell script not wait until the command completes?"

Use do shell script \"command &> file_path &\". do shell script will return immediately with no result and your AppleScript script will be running in parallel with your shell script. The shell script’s output will go into file_path; if you don’t care about the output, use /dev/null.

Example:

do shell script "afplay '/System/Library/Components/CoreAudio.component/Contents/SharedSupport/SystemSounds/dock/drag to trash.aif' &> /dev/null &"

How about this one:

do shell script "afplay '/System/Library/Components/CoreAudio.component/Contents/SharedSupport/SystemSounds/dock/drag to trash.aif'"

How about this one:

do shell script "afplay '/System/Library/Components/CoreAudio.component/Contents/SharedSupport/SystemSounds/dock/drag to trash.aif'"

Update:

To address your comment, this is covered in Technical Note TN2065 - do shell script in AppleScript under Other Concerns where it says:

"... how do I make do shell script not wait until the command completes?"

Use do shell script \"command &> file_path &\". do shell script will return immediately with no result and your AppleScript script will be running in parallel with your shell script. The shell script’s output will go into file_path; if you don’t care about the output, use /dev/null.

Example:

do shell script "afplay '/System/Library/Components/CoreAudio.component/Contents/SharedSupport/SystemSounds/dock/drag to trash.aif' > /dev/null &"