sonic-visualiser: 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/sonic-visualiser - from package: sonic-visualiser

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

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