normalize-audio: command not found

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/normalize-audio - from package: normalize-audio

You may install the required package with command apt-get install {package}

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