soundconverter: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/soundconverter - from package: soundconverter

You may install the required package with command apt-get install {package}
Error in other languages:
soundconverter: bevel nie gevind nie
soundconverter: comandă negăsită
soundconverter: comando não encontrado
soundconverter: commande introuvable
soundconverter: command not found
soundconverter: käsku ei ole
soundconverter: không tìm thấy lệnh
soundconverter: komanda nerasta
soundconverter: Kommando nicht gefunden.
soundconverter: kommandot finns inte
soundconverter: komut yok
soundconverter: nie znaleziono polecenia
soundconverter: níor aimsíodh an t-ordú
soundconverter: no se encontró la orden
soundconverter: no s'ha trobat l'ordre
soundconverter: opdracht niet gevonden
soundconverter: parancs nem található
soundconverter: perintah tidak ditemukan
soundconverter: príkaz nenájdený
soundconverter: příkaz nenalezen
soundconverter: команда не найдена
soundconverter: командата не е открита
soundconverter: 命令找不到
soundconverter: コマンドが見つかりません