dnoise: 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/dnoise - from package: csound-utils

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

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