my dogs howl whenever i arrive home at times what is the meaning are they...

[JaimeHerrera]

...greeting me? they howl whenever sirens go off which is normal i believe but sometimes they howl when I'm inside house. I live alone and my dogs (german shepards) male 12y female 10y spend all or most of their time alone. Have never received complaints from neighbors but wondering what the howls mean? Thanks.